Laird RM024 User manual

A
RAMP Wireless Module
RM024
Version 3.5

RM024
User Guide
Embedded Wireless Solutions Support Center:
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© Copyright 2017 Laird. All Rights Reserved
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REVISION HISTORY
Version
Date
Notes
Approver
1.0
Initial Version
Chris Downey
2.1
Added firmware changes, updated the name of the
removed old references to LT2510 part numbers,
added new information on cyclic sleep and Antenna
Switch Override. Added a table under Max Power and a
table for the Set Max Power command.
Chris Downey
2.2
Minor grammatical fixes.
Chris Downey
2.3
27 June 2013
PWM output data was corrected to a 39.3846 µS
period vs. 315.077, as was stated previously.
Chris Downey
2.4
12 July 2013
Minor edits, removed Firmware History and references
irrelevant to RM024.
Chris Downey
2.5
10 Oct 2013
Corrected Antenna Select Override information error.
Changed 0x59 to 0x5B
Chris Downey
3.0
10 Dec 2013
Separated Hardware Integration Guide (HIG) from User
Guide information (created two separate documents).
Add Related Documents section.
Sue White
3.1
13 Jan 2014
Added information on FW v2.0, deprecated 50mW
radio versions and added 10mW radio versions
Chris Downey
3.2
14 Sept 2015
Removed deprecated links in Related Documents and
Files
Jonathan Kaye
3.3
16 Mar 2016
Updated to the latest template
Sue White
3.4
31 Jan 2017
Added Status Request command
Jennifer Gibbs
3.5
18 July 2017
Fixed header of RSSI Control (0x68) settings table and
RSSI control table.
Jennifer Gibbs

RM024
User Guide
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© Copyright 2017 Laird. All Rights Reserved
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CONTENTS
RAMP Modules...........................................................................................................................................................4
Overview.................................................................................................................................................................4
Key Features ...........................................................................................................................................................4
Theory of Operation ...................................................................................................................................................5
Server/Client Architecture......................................................................................................................................5
Adjustable RF Data Rate .........................................................................................................................................5
Modes of Operation ...............................................................................................................................................6
Serial Interface Baud Rate ......................................................................................................................................7
Interface Timeout/RF Packet Size ..........................................................................................................................8
Flow Control ...........................................................................................................................................................9
Force 9600 ........................................................................................................................................................... 10
Radio Configurations ........................................................................................................................................... 11
EEPROM Parameters ............................................................................................................................................... 19
Configuring the RM024 ........................................................................................................................................... 29
AT Commands...................................................................................................................................................... 29
Utility Commands ................................................................................................................................................ 31
Status Commands................................................................................................................................................ 33
Command Descriptions ....................................................................................................................................... 35
Serial Firmware Upgrades ....................................................................................................................................... 42
Overview.............................................................................................................................................................. 42
Upgrading Via Windows OEM Configuration Utility ........................................................................................... 42
Upgrading FW Commands................................................................................................................................... 43
Command Descriptions ....................................................................................................................................... 43
Process to Manually Upgrade RM024................................................................................................................. 45
API Operation .......................................................................................................................................................... 46
API Send Data Complete...................................................................................................................................... 46
API Receive Packet .............................................................................................................................................. 46
API Transmit Packet............................................................................................................................................. 47
Related Documents and Files .................................................................................................................................. 48

RM024
User Guide
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RAMP MODULES
Laird RAMP (Range Amplified MultiPoint) modules are designed to provide robust wireless communications for
any number of applications requiring a wireless transport for serial data. RAMP modules feature a Frequency
Hopping Spread Spectrum (FHSS) protocol for excellent interference and multipath immunity. RAMP modules
server/client architecture allows for more than 16 million clients to be addressed and communicating within the
network.
Overview
The RM024 RAMP module is based on Laird LT2510 core technology, enhanced with a new RF front end for
improved sleep, improved link budget, and a switchable antenna output. The RM024 is available in two versions,
one with 125 mW maximum conducted output power which is approved for North American and similar
markets, and one with 10 mW maximum conducted output power which is approved for European and similar
markets. These modules are identical except for output power, transmit power consumption, and the number of
RF channels available. Differences between the two versions, where applicable, are denoted based on part
number.
This document contains information about the hardware and software interface between a Laird RM024
transceiver and an OEM host. Information includes the theory of operation, specifications, interface definitions,
and mechanical drawings.
Note: Unless mentioned specifically by name, the RM024 modules are referred to as “radio” or
“transceiver”. Individual naming is used to differentiate product specific features. The host
(PC/microcontroller/any device to which the RM024 module is connected) are referred to as “OEM
host” or “host.”
Key Features
Forward Error Correction option for longer range
Retries and acknowledgements
Configurable network parameters
Multiple generic I/O
280 kbps or 500 kbps RF data stream
Idle current draw of 9.5 mA, sleep current of 38 uA
Software selectable interface baud rates from 1200 bps to 460.8 kbps
Upgradable FW through serial port
Low cost, low power, and small size ideal for high volume, portable, and battery powered applications
All modules are qualified for Industrial temperatures (-40°C to 85°C)
Advanced configuration available using AT commands
Easy to use Configuration and Test Utility software
Switchable antenna output, either integrated antenna or external antenna through U.FL

RM024
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THEORY OF OPERATION
Server/Client Architecture
The RM024 utilizes server-client network architecture to synchronize the frequency hopping. Each network must
have one radio configured as a server and all other radios configured as clients. When a radio is configured as a
server, it transmits a beacon containing timing and identification information at the beginning of each hop. The
beacon is never visible to the OEM host. Upon boot, radios configured as clients enter receive mode where they
are scanning the available frequencies listening for a beacon from a server in their network. When a client
detects the server’s beacon, the client synchronizes its frequency hopping to that of the server and transition
the In Range pin Low. When the server and the client are synchronized they can begin transferring data.
Each network consists of only one server. Multiple networks can exist in the same area, provided the networks
are configured on different channels. The RM024 utilizes an intelligent Frequency Hopping algorithm which
ensures minimal interference between networks. The possible interference between collocated networks is
given by the following equation:
Maximum number of interfering bins = # of collocated servers -1
For example, with ten collocated networks, there is up to nine bins every hop cycle that are occupied by more
than one network at the same time. Although two or more networks might occupy the same hop bin at the
same time, there is truly only interference if two or more radios from alternate networks are trying to transmit
on the same bin at the same time in the same coverage area.
Adjustable RF Data Rate
The RM024’s RF data rate can be adjusted to provide a trade-off between throughput and range.
Table 1: RM024 RF Data Rate
Product Model
RF Profile
RF Data Rate
Number of Hops
Receiver Sensitivity
Throughput1
All RM024
0x00
500 kbps
43
-94 dBm
250 kbps
125 mW versions
(RM024-X125) only
0x01
280 kbps
79
-95 dBm
120 kbps
All RM024
0x03
280 kbps
43
-95 dBm
120 kbps
1. Throughput is ideal, one direction, with no retransmissions. All practical RF applications should allow for
retransmission of data due to interference or less than ideal RF conditions.
Deciding which RF data rate to choose depends on the individual application. The fast RF data rate delivers much
faster throughput, but has much less range. In addition, because the lower data rate solution uses more hops, it
is better situated for collocated networks.
A rule of thumb for RF systems is every six dB of gain doubles the effective distance. The four dB increase of
receive sensitivity for the lower data rate solution means it is able to transmit almost 60% further than the
higher data rate solution.

RM024
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Modes of Operation
The RM024 has three different types of interface modes:
Transparent Mode
API Mode
Command Mode
The first two modes are used to transmit data across the RF and the third mode is used to configure the radio.
Transparent Mode
When operating in transparent mode, the RM024 can act as a direct serial cable replacement in which RF data is
forwarded over the serial interface and vice versa. In transparent mode, the radio needs to be programmed with
the MAC address of the desired recipient. The destination address can be programmed permanently or on-the-
fly.
When transparent mode is used, data is stored in the RX buffer until one of the following occurs:
The RF packet size is reached (EEPROM address 0x5A)
An Interface timeout occurs (EEPROM address 0x58)
All parameters can be configured by entering Command Mode using either AT commands or by toggling the
Command/Data pin low on the transceiver.
Transparent mode is the default radio operation mode.
API Mode
API mode is an alternative to the default transparent operation of the RM024 and provides dynamic packet
routing and packet accounting abilities to the OEM host without requiring extensive programming by the OEM
host. API mode utilizes specific frame-based packet formats, specifying various vital parameters used to control
radio settings and packet routing on a packet-by-packet basis. The API features can be used in any combination
that suits the OEM’s application specific needs.
The RM024 has three API functions:
Send Data Complete
Receive API
Transmit API
For additional details and examples, please refer to the API Operation section of this guide.
Command Mode
Command mode is used to configure and poll for status of the transceiver. Command mode can be entered by
issuing the Enter AT Command string or by setting the CMD/Data pin low. Details of using command mode to
configure the RM024 are detailed in Configuring the RM024.

RM024
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Serial Interface Baud Rate
In order for the OEM host and a transceiver to communicate over the serial interface, they must have the same
serial data rate. This value determines the baud rate used for communicating over the serial interface to a
transceiver. For a baud rate to be valid, the calculated baud rate must be within ±3% of the OEM host baud rate.
Table 2: Baud Rate/Interference Rate
Desired Baud Rate
Baud (0X42)
Minimum Interface Timeout 1 (0X58)
230400
0x0A
0x02
1152002
0x09
0x02
57600
0x08
0x02
38400
0x07
0x02
28000
0x06
0x03
19200
0x05
0x05
14400
0x04
0x07
9600
0x03
0x10
4800
0x02
0x15
2400
0x01
0x2A
1200
0x00
0x53
Non-standard
0xE3
Use equation below
1. Interface timeout = 200 µs per increment, the EEPROM address 0x58 is ignored if Auto Config is enabled.
To use a non-standard Interface timeout, disable Auto Config.
2. Default baud rate.
For baud rates other than those shown in Table 2, the following equations can be used:
(256 + BAUD_M * (2BAUD_E) * FREQUENCY
Baud Rate = ___________________________________
228
Where:
FREQUENCY = 26 MHz
BAUD_M = EEPROM Address 0x43
BAUD_E = EEPROM Address 0x44
100000
Minimum Interface Timeout = _______
Baud Rate
Tips:
The RM024 supports a majority of standard as well as non-standard baud rates. To select a standard baud
rate, use the value shown for EEPROM address 0x42 in Table 2. To enable a non-standard baud rate,
program EEPROM address 0x42 (Custom Baud Enable) to 0xE3 and then use the equation above to solve for
BAUD_M and BAUD_E.
Adjusting the serial interface baud rate does not affect the RF data rate.
Radio can accept serial combinations (number of bits, parity, number of stop bits) of 8-N-1, 7-N-2, 7-1-1, by
default. Modes of 8-1-1, 8-N-2, 7-1-2 are acceptable with 9-bit mode enabled.

RM024
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Interface Timeout/RF Packet Size
Interface Timeout
Interface timeout specifies a maximum byte gap between consecutive bytes. When that byte gap is exceeded,
the bytes in the transmit buffer are processed as a complete packet. Interface timeout (EEPROM address 0x58),
in conjunction with the RF packet size, determines when a buffer of data is sent out over the RF as a complete
RF packet, based on whichever condition occurs first. Interface timeout is adjustable in 200 us increments and
should be equal to or greater than two full bytes times. The minimum interface timeout is 0x02.
The radio uses the default interface timeout for a given baud rate if Auto Config is enabled, despite what is
written in the interface timeout address. To use a non-standard interface timeout, the OEM needs to disable
Auto Config.
RF Packet Size
RF packet size is used in conjunction with interface timeout to determine when to delineate incoming data as an
entire packet based on whichever condition is met first. When the transceiver receives the number of bytes
specified by RF packet size (EEPROM address 0x5A) without experiencing a byte gap equal to interface timeout,
that block of data is processed as a complete packet. Every packet the transceiver sends over the RF contains
extra header bytes not counted in the RF packet size. Therefore, it is much more efficient to send a few large
packets than to send many short packets. The maximum RF packet size is 239 bytes, or 0xEF, at 500 kbps RF data
rate and 96 bytes, or 0x60, at 280 kbps RF data rate.
The RF packet size in address 0x5A will not be used if Auto Config (Address 0x56, bit 0) is enabled. The default
for the RF data rate will be used instead. The RF packet size should not be set to less than 0x07, to ensure AT
commands can still be issued.
RF packet size is also used by the radio to determine the number of data slots per hop. In order to efficiently
transmit data across the RF the radio automatically adds more data slots to the hop to correspond to a smaller
RF packet size. The number of slots available is reduced when FEC mode is enabled. The number of slots per hop
is given in the table below.
Table 3: Number of Slots per Hop
RF Data Rate
FEC Mode
RF Packet Size
Number of Data Slots
280 kbps
Disabled
0x01 –0x09
4 slots
280 kbps
Disabled
0x0A –0x25
3 slots
280 kbps
Disabled
0x26 –0x60
2 slots
500 kbps
Disabled
0x01 –0x0C
6 slots
500 kbps
Disabled
0x0D –0x25
5 slots
500 kbps
Disabled
0x026 –0x47
4 slots
500 kbps
Disabled
0x48 –0x7D
3 slots
500 kbps
Disabled
0x7E –0xEF
2 slots
280 kpbs
Enabled
0x01 –0x06
2 slots
280 kpbs
Enabled
0x07 –0x4A
1 slot
500 kbps
Enabled
0x01 –0x02
4 slots
500 kbps
Enabled
0x03 –0x1A
3 slots
500 kbps
Enabled
0x01B –0x4B
2 slots
500 kbps
Enabled
0x4C –0xE2
1 slot

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Tips:
The more slots per hop, the less likely that retries will occur on a new frequency which may reduce the
effectiveness of the module as a Frequency Hopping radio.
Idle current consumption increases as more slots are added.
You must use the same number of slots for every radio on the network.
Full duplex only reserves the first slot for the server. If there are six slots, the first slot is reserved for the
server to transmit and the remainder is shared by the clients. If there is only one slot per hop available, the
Server and Client will alternate transmissions with the Server transmitting in one slot/hop and the client
transmitting on the next hop.
RF Packet Size should not be set to less than 0x07 or the Enter AT Command string will not be accepted. If
the RF Packet Size is less than 0x07, the Enter AT Command string can still be issued in Force 9600 mode.
RS-485 Data Enable
The timing of the DE-RE pin varies depending on the selected interface baud rate. The values to set are:
485_Delay_H: Address 0x49
485_Delay_M: Address 0x4A
485_Delay_L: Address 0x4B
To set them, use the following equation (round the result up):
Address 0x49 and 0x4A: 485H/M = 8.125 MHz / (81*Baud_Rate), quotient only
Address 0x4B: 485L = (8.125MHz / Baud_Rate) mod 81
So for 19,200 you should calculate 00 05 12.
Flow Control
Although flow control is not required for transceiver operation, it is recommended to achieve optimum system
performance and to avoid overrunning the RM024’s serial buffers. The RM024 uses separate buffers for
incoming and outgoing data.
RXD Data Buffer and CTS
As data is sent from the OEM host to the radio over the serial interface, it is stored in the RM024’s buffer until
the radio is ready to transmit the data packet. The radio waits to transmit the data until one of the following
conditions occur (whichever occurs first):
The RF packet size is reached (EEPROM address 0x5A)
An interface timeout occurs (EEPROM address 0x58)
The data continues to be stored in the buffer until the radio receives an RF Acknowledgement (ACK) from the
receiving radio (addressed mode), or all transmit retries/broadcast attempts are used. Once an ACK has been
received or all retries/attempts are exhausted, the current data packet is removed from the buffer and the radio
begins processing the next data packet in the buffer.
To prevent the radio’s RXD buffer from being overrun, we strongly recommend that the OEM host monitors the
radio’s CTS output. When the number of bytes in the RXD buffer reaches the value specified by CTS_ON
(EEPROM address 0x5C - 0x5D), the radio de-asserts (high) CTS to signal to the OEM host to stop sending data
over the serial interface. CTS is re-asserted after the number of bytes in the RXD buffer is reduced to the value
specified by CTS_OFF (EEPROM addresses 0x5E- 0x5F); signaling to the OEM host that it may resume sending
data to the transceiver.

RM024
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Note: We recommend that the OEM host stop all data transmission to the radio while CTS is de-asserted
(high), otherwise potential data loss may occur.
TXD Data Buffer and RTS
As data to be forwarded to the OEM Host accumulates, it is stored in the RM024’s outgoing buffer until the
radio is ready to begin sending the data to the OEM Host. Once the data packet has been sent to the Host over
the serial interface, it will be removed from the buffer and the radio will begin processing the next data packet
in the buffer. With RTS Mode disabled, the transceiver will send any data to the OEM Host as soon as it has data
to send. However, some OEM Hosts are not able to accept data from the transceiver all of the time. With RTS
Mode Enabled, the OEM Host can prevent the transceiver from sending it data by de-asserting RTS (High),
causing the transceiver to store the data in its buffer. Upon asserting RTS up to two additional bytes can be
received over the serial interface before the flow is stopped. Once RTS is re-asserted (Low), the transceiver will
continue sending data to the OEM Host, beginning with any data stored in its buffer.
Note: Leaving RTS de-asserted for too long can cause data loss once the radio’s TXD buffer reaches
capacity.
Note: RTS is disabled in Force 9600 mode in Firmware 2.0 and above.
Tip:
Can I implement a design using just TXD, RXD, and GND (three-wire interface)?
Yes. However, it is strongly recommended that your hardware monitor the CTS pin of the radio. CTS is taken
High by the radio when its interface buffer is getting full. Your hardware should stop sending at this point to
avoid a buffer overrun (and subsequent loss of data). You can perform a successful design without monitoring
CTS. However, you need to take into account the amount of latency the radio adds to the system, any additional
latency caused by retries, how often you send data, non-delivery network timeouts, and interface data rate.
Laird Technologies can assist in determining whether CTS is required for your application.
Force 9600
Force 9600 mode is a recovery mode in which the radio ignores specific EEPROM configurations. Force 9600
mode is primarily used to recover a radio when the configuration is not known.
Enabling Force 9600
Force 9600 is triggered by the Force 9600 pin (pin 12 for SMT modules and pin 9 for pluggable modules). When
you pull the Force 9600 pin logic low and apply power or reset the module, the transceiver’s serial interface is
forced to a 9600, 8-N-1 rate. Additional RTS Enable is disabled and the RF Packet Size in EEPROM is ignored.
The Radio’s receiver is disabled in Force 9600 mode, so it is unable to receive beacons or packets.
Note: Because this mode disables some modes of operation, it should not be permanently pulled Low
during normal operation.

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Radio Configurations
Antenna Switch (EEPROM 0xC1, bit 5)
Selects either integrated chip antenna or U.FL connector for external antenna.
Note: On RM024 –C units with no integrated antenna, the RF switch is still active and it is possible,
though not advised to switch to the integrated antenna option, even though there is no antenna
connected. RF performance in this configuration would be degraded. See Antenna Select Override
for additional options.
Antenna Select Override (EEPROM 0x5B)
Disables the antenna switch on –C products causing the firmware to ignore the setting in Antenna Switch and
use the U.FL port automatically.
Note: Product ID’s containing an “M” (RM024-S125-M-01, RM024-P125-M-01, RM024-S50-M-01 and
RM024-P50-M-01) have both antennas installed (chip antenna and u.FL). However, products
containing a “C” (RM024-S125-C-01, RM024-P125-C-01, RM024-S50-C-01 and RM024-P50-C-01)
only have the u.FL installed. Therefore, selecting chip antenna on a “C” product results in no RF
link. This feature does not work in FW v1.3-0 on 50 mW radios (RM024-x50-C-01).
Auto Channel (EEPROM 0x56, bit 3)
To allow for more flexible network configurations, Auto Channel can be enabled in clients to allow them to
automatically synchronize with the first server they detect, regardless of channel number.
Note: A client with Auto Channel only synchronizes with a server that has a matching System ID.
Auto Config (EEPROM 0x56 bit 0)
The optimal settings for interface timeout and RF packet size vary according to the selected RF profile and
interface baud rate. Enabling Auto Config bypasses the value for these variables stored in EEPROM and uses
predetermined values that have been optimized for the given mode. When Auto Config is disabled, these values
must be programmed in the transceiver EEPROM.
Auto Destination (EEPROM 0x56, bit 4)
To simplify EEPROM programming, Auto Destination can be enabled in the radio which allows the radio to
automatically set its destination to the address of the radio from which it last received a successful transmission
from (beacon or data packet).
Auto Destination on Beacons Only (Address 0x56, bit 7)
When Auto Destination is enabled, the client radio addresses itself to the source of any received packet,
including beacons from the server and any addressed or broadcast packets it receives. For point to multipoint
networks where the client is intended to only communicate back to the server, this could cause the client to
inadvertently become addressed to another client. By enabling Auto Destination on Beacons Only, the client
only addresses itself upon reception of beacons, therefore it only addresses itself to the server. Auto Destination
on Beacons Only is only functional when Auto Destination is also enabled.

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Auto System ID (EEPROM 45, bit 4)
When enabled, Auto System ID allows a client to attach to any server on the same RF channel, regardless of the
System ID on the server or the client.
Beacon Skip (EEPROM 0x6F)
When set, the transceiver will send (server) or listen (client) for a beacon on hops spaced by the Beacon Skip
number. On a client, once the Beacon Skip count is reached the client will listen every hop until it successfully
hears a beacon. It will then wait a number of hops specified by the Beacon Refresh before listening again.
Enabling this will allow the transceiver to conserve power by disabling its RF circuitry during the beacon time.
Enabling this on the server causes substantially longer sync times on the clients.
Broadcast (EEPROM 0xC1, bit 7)
In Broadcast mode, the transceiver transmits the packet to all transceivers with the same Channel Number and
System ID settings. There is no RF acknowledgement sent from the recipient(s) back to the transmitter,
therefore the packet is sent out the number of times specified by Broadcast Attempts.
Broadcast Attempts (EEPROM 0x4D)
When transmitting broadcast packets, the RF packet is broadcast out to all eligible receivers on the network.
Broadcast Attempts is used to increase the odds of successful delivery to the intended receivers. Transparent to
the OEM host, the transmitter sends the RF packet to the receivers. If a receiver detects a packet error, it throws
out the packet. This continues until the transmitter exhausts all of its attempts. Once the receiver successfully
receives the packet, it sends the packet to the OEM host. It throws out any duplicates caused by further
broadcast attempts. The received packet is only sent to the OEM host if it is received free of errors. Because
broadcast packets have no RF acknowledgement, each packet is transmitted the number of times specified by
Broadcast Attempts. This makes for inefficient use of the available bandwidth; therefore, it is recommended
that Broadcast Attempts be set as low as possible and that broadcast packets be limited in use.
Note: Setting to 0 is equal to 256.
Cyclic Sleep (EEPROM 0x61, bit 0)
Causes the radio to sleep for a programmable period of time and wake for a programmable period of time. The
radio can be awakened from sleep before its sleep cycle completes using the Force 9600 pin. Additionally, the
wake time is an inactivity counter. Therefore, the device stays awake indefinitely as long as the device continues
sending packets over the RF interface.
Destination Address (EEPROM 0x79-0x75)
The Destination Address is simply the MAC (IEEE) address of the intended receiver on the network. In Addressed
mode, the RF packet is sent out to the intended receiver designated by the destination address. Only the four
LSBs (Least Significant Bytes) of the destination address are actually used for packet delivery. This field is ignored
if Broadcast mode, Auto Destination, or Transmit API is enabled.
Disable Status Bin (EEPROM 0xC1, bit 4)
When set, disables the reception on the status slot of the bin. The result is that the bin analyzer and remote I/O
functionality is disabled on the radio with the benefit of saving approximately 1 mA average current
consumption.

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Discard Framing Error Packets (EEPROM 0x57, bit 7)
When set, the radio checks for a framing error in the UART buffer before processing incoming data. If an error is
detected on any of the bytes in the buffer, the entire buffer is discarded.
Forward Error Correct (See RF Profile for configuration information)
Specific RF Profiles are reserved to enable Forward Error Correction (FEC). Forward Error Correction can be used
to decrease the packet error rate in the presence of bursty errors over the air. The RM024 uses convolutional
coding and interleaving to allow the receiver to recover from small bit errors. When enabled, FEC will cause the
radio to transmit additional bits of data over the air to allow for error recovery. When FEC is enabled the
maximum RF Packet size is decreased, the number of data slots may be reduced and the throughput of the radio
can be reduced as much as half of non-FEC mode. FEC is most useful when near the receiver sensitivity limit, but
due to the nature of the shared nature of the 2.4 GHz ISM bands, can provide improvements in packet error rate
even when the signal strength is strong. Though FEC does not increase the receiver sensitivity or affect the link
budget, in real-world range tests, FEC enabled had as much as a 3dBm equivalent improvement.
FEC is enabled by selecting one of the following RF Profiles.
0DH: 500kbps (1.5MHz steps) + FEC, 43 hops, 2.4GHz 500kbps RF
0EH: 280kbps (900kHz steps) + FEC, 79 hops, 2.4GHz (FCC Only)
0FH: 280kbps (900kHz steps) + FEC, 43 hops, 2.4GHz (FCC Only)
10H: 280kbps (1.5MHz steps) + FEC, 43 hops, 2.4GHz 280kbps RF
Full Duplex (EEPROM 0x56, bit 1)
In Half Duplex mode, the transceiver sends a packet out over the RF immediately. This can cause packets sent at
the same time by a server and a client to collide with each other over the RF. To prevent this, Full Duplex mode
can be enabled. This mode reserves a transmit “slot” for the server. If the server does not have any data to
transmit, clients are permitted to transmit during that time. If the server does have data to send, clients will not
be permitted to transmit during that slot. Likewise, the server will not be able to transmit during a client slot.
Though the RF hardware is still technically half duplex, it makes the transceiver seem full duplex. This can cause
overall throughputs to be cut in half.
Note: All transceivers on the same network must have the same setting for Full Duplex.
Hop Packet Delineation (EEPROM 0x57, bit 6)
When enabled, in addition to using RF packet size and interface timeout as criteria for processing incoming data,
the radio also delineates packets up to once per hop once a minimum of six characters has been received over
the serial port.
Legacy RSSI (EEPROM 0x45, bit 2)
RSSI (Received Signal Strength Indicator) is a measure of how well the receiving radio is able to hear the
transmitting radio. By default, RSSI is reported in 8-bit 2’s complement hexadecimal format; therefore, values
range from 0x80 - 0x7F. Many preceding products have, instead, reported RSSI in the range of 0x00 - 0xFF.
Legacy RSSI causes 0x80 to be added to the RSSI result prior to reporting it to the host.

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Max Power (EEPROM 0x63)
On 50mW and 125mW RM024 radios, the transceiver has an adjustable RF output power. Power can be
adjusted dynamically to optimize communications reliability and conserve power. Each increment represents a 3
dBm 50% decrease in power. The radios have a maximum input RF level of 0 dBm. When operated very close
together at full power, the radio’s receiver can saturate and no transmissions are possible. If the distance
between the transmitter and receiver is very short (generally less than 2 ft or 0.6 m with 2.5 dBi antennas), the
maximum power should be reduced.
On 10mW RM024 radios, the Max Power setting will have no effect on the output power, all four power settings
are fixed at 10mW.
Mode (Server/Client) (EEPROM 0x41)
The server controls the frequency hop timing by sending out regular beacons (transparent to the transceiver
host) which contain system timing information. This timing information synchronizes the client radio frequency
hopping to the server. Each network should consist of only one server.
Nine Bit Mode (EEPROM 0x57, bit 1)
With Nine Bit mode disabled, the transceiver communicates over the asynchronous serial interface in 8-N-1
format (8 data bits, No parity, 1 stop bit). Some systems require a parity or 9th data bit. Enabling Nine Bit mode
causes the transceiver to communicate using 8-1-1 format (8 data bits, 1 parity bit, 1 stop bit). In this mode, the
transceiver does not validate the parity bit but simply transmits it over the RF. This is useful as some systems use
the ninth bit as an extra data bit and not just a parity bit. However, because the ninth bit is transmitted over the
RF, enabling Nine Bit mode cuts the transceiver interface buffer size by 1/9 and reduces the RF bandwidth by the
same ratio.
Random Backoff (EEPROM 0xC3)
The transceivers utilize a retry protocol with Random Backoff and a programmable back-off seed. Therefore, in
the event an acknowledgement is not received, the transceiver backs off and retries the packet. For example,
when two transceivers collide with each other (transmitting packets at the same time), each transceiver chooses
a random number of packet times that it will wait before retrying the packet. Ideally, they each choose a
different number and are successful in the next transmission. A good rule of thumb is to set Random Backoff to
a number slightly larger than the maximum number of transceivers that would be expected to be transmitting at
the same time. When set to transmit broadcast packets, where there is no acknowledgment available, the
Random Backoff value is used for all subsequent attempts.
Range Refresh (EEPROM 0x3D)
Range refresh specifies the maximum amount of time a transceiver reports In Range without having heard a
server’s beacon. It is adjustable in hop periods. Do not set to 0.
Remote I/O Mode (Address 0x57, bit 3)
Remote I/O mode allows GPIOs on two radios to be joined together so their states are reflected on the other
radio. Enabling Remote I/O mode allows the local radio to transmit its GPIO states whenever there is a change.
The states are transmitted to the radio specified by the Destination Address (or as a broadcast if Broadcast
mode is enabled). State information is only transmitted when there is a change on one of the enabled Digital
Inputs. The states are retransmitted up to the number of specified Utility Retries (Address 0x4E). Any changes to
the Digital Inputs that occur while a utility retransmission is occurring are not transmitted unless the change
persists until all utility retries have been sent or an acknowledge was received. Therefore, this feature should

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only be used for slow-moving changes that occur less than the time it takes to expend all retries. Remote I/O is
disabled when the Force 9600 pin is set at boot.
Remote I/O control lines occur in pairs, with the Digital Input on the local radio driving a Digital Output on the
remote radio and vice-versa. This makes Remote I/O useful for both point-to-point and point-to-multipoint
networks. Multipoint-to-point networks do not benefit from using a single pair of lines as the central point isn’t
able to tell where the line change was sourced. Multiple control lines are available though, so up to four pairs of
lines can be used simultaneously. Likewise, analog inputs can be used (Address 0x57, bit 4) as the input (with a
PWM output on the remote radio), though analog states are only transmitted when a utility packet is sent,
which are only triggered by the change of a Digital Input. Threshold settings are not available on analog Inputs.
Output lines are initialized at boot according to Remote I/O Status (Address 0xC9-0xCA) for the digital lines and
PWM_Init (Address 0xC8) for the PWM output.
Which control lines are used in Remote I/O is set by the Remote I/O Control bit field (Address 0x60). Note that
TxD/RxD is one pair of Remote I/O lines available. If this pair is used, the module does not respond to commands
and is not able to transmit or receive serial data. If this pair is enabled, Force 9600 must be low at boot to
disable Remote I/O if serial communications are desired.
Table 4: Remote I/O Control bit fields (Address0x60)
Address 0x60, Bit
Input
Output
Bit 0 set
GIO_4
GIO_0
Bit 1 set
GIO_81
GIO_1
Bit 2 set
GIO_7
GIO_3
Bit 3 set
CMD/Data
GIO_2
Bit 4 set
RTS
CTS
Bit 5 set
RXD
TXD
Bit 6 clear, Bit 7 clear
All I/O are Outputs
Bit 6 set, Bit 7 clear
All I/O are Inputs
Bit 7 set
Inputs and outputs are as specified in table
1. GIO_8 (Pin 18) on board revisions 0050-00203 Rev 0 and 0050-00196 rev 2 (and below) is internally not
connected. This pin is unavailable as a GPIO on these boards.
Tips:
When using GIO_7/GIO_3 Pairs, the input/output will be digital unless Remote Analog Enable bit is set
(Address 0x57, bit 4) in which case the input is Analog and the output is PWM.
TXD and RXD are not available for UART serial data when used as in Remote I/O. Force 9600 must be Low
on boot to disable Remote I/O Mode and issue commands.
When not using pairs (bit 7 clear), one radio should have all I/O as inputs and the other radio or radios
should have all I/O as output.
Remote I/O Mode must be enabled on both the local and remote radio and the Remote I/O Control Bit
must be set for the same pair on both radios.
All I/O state information for all lines is transmitted when any update is triggered. Thus, on the receiving
radio any enabled output pins will be updated, regardless of whether those pins were enabled on the
transmitting radio.

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RF Channel Number (EEPROM 0x40)
This product uses FHSS (Frequency Hopping Spread Spectrum) protocol in which the transceiver communicates
using frequency “bins” spaced throughout the frequency band. Therefore, RF Channel Number specifies a
unique pseudo-random hopping sequence.
RF Profile (EEPROM 0x54)
RF Profile can be adjusted to provide a trade-off between throughput and range. Deciding which RF profile to
choose depends on the individual application. Selecting a higher RF baud rate provides increased RF bandwidth.
However, selecting the lower RF baud rate provides significantly improved range. Selecting fewer hops provides
a shorter sync time, whereas more hops provides better interference and collocated system immunity. Forward
Error Correction (FEC) is also enabled by selecting an appropriate RF Profile. FEC will further increase the range
of the radio and allow for less packet errors in the presence of bursty RF interference. FEC will affect the reduce
maximum RF Packet Size available, reduce the number of data slots per hop and the reduce the overall
throughput of the radio.
RSSI
Received Signal Strength Indicator (RSSI) is available to the OEM through a number of means. AT commands
such as Get Last RSSI and Bin Analyzer report RSSI, API Packets for Receive API and Send Data Complete report
RSSI, and one of three pins can be configured to provide a PWM output representing the RSSI. By default, AT
commands and API packets represent RSSI in an 8-bit hexadecimal 2’s complement range. Legacy RSSI (detailed
above) can be enabled to provide the RSSI in a non 2’s complement form from 0x00 (very weak signal) to 0xFF
(very strong signal). The control commands for PWM output utilize a Legacy RSSI format from 0x00 to 0xFF.
The RSSI values reported can be converted to a decibel value with the following formulas:
For Non-Legacy values where the RSSI is reported in 8-bit 2’s complement hexadecimal ranging from 0x80
to 0x7F, use the following to calculate the RSSI_dBm. For these calculations, convert the reported
hexadecimal value directly to decimal notation, ignoring the 2’s complement conversion:
–If this value is greater than or equal to 128, then:
RSSI_dBm = (RSSI_Dec - 256)/2 - RSSI_Offset
–If this value is less than 128, then:
RSSI_dBm = (RSSI_Dec)/2 - RSSI_Offset
For Legacy RSSI the equation is:
–RSSI_dBm = (RSSI_Dec - 128)/2 -RSSI_Offset
–RSSI_Dec is the reported value represented in Decimal notation
–RSSI_Offset = 82
Reported RSSI values are meant as estimates and have an accuracy of +/- 2 dBm. The RSSI reported by various
commands has an effective range of -25 dBm to -95 dBm. Outside of this range, the accuracy is not maintained.
RSSI_Control (EEPROM 0x68)
RSSI Control is a bit field used to control the output of the RSSI PWM output and what messages the radio
reports on.
Note: If Disable Hop Frame is disabled (so as to report Hop Frame), it is output on GO_0 (pin 1 of SMT
module); therefore, the PWM output should not be set to output to that pin or conflicting signals
will be sent on that output pin.

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Table 5: RSSI Control
Address 0x68, Bit
Description
bit 0 set
Update RSSI on Beacons
bit 1 set
Update RSSI on Addressed Packets
bit 2 set
Update RSSI on Broadcast Packets
bit 3 set
Update RSSI on Unintended Packets
bit 4 set
Invert RSSI Output
bit 5 set
Moving Average on RSSI Pin
bit 6 set
RSSI Pin Location 0
bit 7 set
RSSI Pin Location 1
RSSI_Lag (EEPROM 0x67)
Controls a filter on the PWM output to smooth out the changes made to the PWM signal.
Setting the value to a very low number results in very quick changing output.
Setting the value to a higher number results in a slower varying PWM output.
Setting the value to 0x00 results in an instantaneous RSSI.
Because RSSI is measured per hop and the radio can hop over 43 or 79 hops, instantaneous RSSI may move too
quick to be of use as a signal strength indicator. The default value is 0x40 and should be sufficient for most
applications. It should be set to a value of less than 0x80.
RSSI_Lag affects the PWM Output according to the following equations:
Cumulative_Lag = Cumulative_Lag + (RSSI_Current –Old_RSSI_Avg)
New_RSSI_Avg = Old_RSSI_Avg + (Cumulative_Lag mod EE_Lag)
Cumulative_Lag is then stored in memory until the next time RSSI is calculated.
If (Cumulative_Lag mod EE_Lag) > 0, then Cumulative_Lag = remainder of (Cumulative_Lag mod EE_Lag)
RSSI Output to PWM
A moving RSSI average can be written to the PWM Output as a signal strength indicator. The output pin to use,
the threshold range for the RSSI and the RSSI Type reported can all be configured through EEPROM addresses.
The PWM output has a 39.3846 µS period. The duty cycle is set by the RSSI value recorded by the transceiver
and the RSSI Threshold High and RSSI Threshold Low values.
RSSI Threshold High (EEPROM 0x65)
The upper limit of the recorded RSSI reading. RSSI Values reported above this value (strong signals) report a
100% duty cycle on the PWM output.
RSSI Threshold Low (EEPROM 0x66)
The lower limit of the recorded RSSI reading. RSSI Values reported below this value (weak signals) report a 0%
duty cycle on the PWM output.
To calculate the thresholds, use the following equation:
RSSI_Dec = (RSSI_dBm + 82) * 2 +128
Then convert this from decimal to hexadecimal notation.

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Sleep Indicator (EEPROM 0x45, bit 6)
When enabled, GIO_1 toggles low during sleep and high when the module is awake.
Sleep Timer High/Low (EEPROM 0xCD-0xCE)
Two bytes to indicate the length of time to sleep in seconds.
Wake Count (EEPROM 0xCF)
Time in number of hops (13.19 ms each) to stay awake during cyclic sleep. This counter is an inactivity counter,
therefore the counter is reset as long as the device continues to transmit packets over the RF interface.
Note: Once the Wake Counter has expired, the radio waits for a slot of inactivity (meaning that no RF
packet is being received/transmitting, the serial port is idle, and the radio is not in AT Command
mode). Once all of these conditions are met, the radio enters its sleep cycle. To prevent the radio
from entering its sleep cycle or to force it out of its sleep cycle, the 9600 baud pin can be held low.
Sniff Permit (EEPROM 0x45, bit 0)
Sniff Permit allows a radio to receive a data packet from another radio on the network regardless of the
destination MAC address in the packet. This allows an OEM to create a sniffer for all network traffic. Sniff Permit
must be enabled on the transmitting radio to grant its permission to be heard. Sniff Report and Sniff Permit
must be enabled on the sniffer radio to cause it to send sniffed packets out the serial port.
System ID (EEPROM 0x76)
System ID is similar to a password character or network number and makes network eavesdropping more
difficult. A receiving transceiver will not go in range of or communicate with another transceiver on a different
System ID. System ID can be ignored on a client by enabling Auto System ID.
Transmit Retries (EEPROM 0x4C)
When transmitting addressed packets, the RF packet is sent out to the receiver designated by its destination
address. Transmit Retries is used to increase the odds of successful delivery to the intended receiver.
Transparent to the OEM host, the transmitter sends the RF packet to the intended receiver. If the receiver
receives the packet free of errors, it sends the transmitter an acknowledgement. If the transmitter does not
receive this acknowledgement, it assumes the packet was never received and retries the packet. This continues
until the packet is successfully received or the transmitter exhausts all of its retries. The received packet is only
sent to the OEM host if and when it is received free of errors.
Note: Setting to 0 is equal to 256.
Unicast Only (EEPROM 0xC1, bit 3)
To prohibit transceivers from receiving broadcast packets, Unicast Only can be enabled. Unicast Only restricts
the transceiver to only receive addressed packets.

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Vendor ID
The Vendor ID, like the System ID, can be used to uniquely identify a network. Radios with the Vendor ID set,
only communicate with other radios with the same set Vendor ID.
The Vendor ID is a protected EEPROM parameter and its value cannot be read. It can only be written once.
OEMs should be aware that improperly setting the Vendor ID can cause communication issues. Setting the
Vendor ID to an unknown setting effectively renders the radio unable to communicate in a network.
Note: The Vendor ID is a one-time write parameter; it cannot be read.
9600 Boot Option (EEPROM 0x57, bit 0)
When enabled, 9600 Boot Option causes the 9600 pin to be ignored on cold boot (power-up) and brown-out
conditions. Therefore, the 9600 pin is only observed on warm boots (reset pin toggled). This can be helpful so
that brown-out conditions don’t cause the baud rate to change if the 9600 pin happens to be low at the time.
When 9600 Boot Option is disabled, the 9600 pin is used for warm and cold boots as well as brown-out
conditions.
EEPROM PARAMETERS
The RM024 utilizes a server-client network architecture to synchronize the frequency hopping. Each network
must have one radio configured as a server and all other radios configured as clients. When a radio is configured
as a server, it transmits a beacon at the beginning of each hop. Radios configured as clients default to a receive
mode where they are scanning the available frequencies listening for a beacon from a server in their network.
When a client detects the server’s beacon, the client synchronizes to it and transitions the In Range pin low.
When the server and the client are synchronized, they can begin transferring data.
Table 6: EEPROM Parameters
Parameters
EEPROM
Address
Length
(Bytes)
Range
Default
Description
Product ID
0x00
0x23
Product identifier string, includes revision
information for software and hardware.
Range
Refresh
0x3D
1
0x01-0xFF
0x48
Specifies the maximum amount of time a
transceiver reports In Range without having
heard a server’s beacon. Equal to hop
period * value, do not set to 0x00.
Channel
Number
0x40
1
79 Hops:
0x00 –0x4D,
43 Hops:
0x00 –0x29
0x00
Selects a unique hopping sequence in order
to demarcate collocated networks.
Mode:
Server/Client
0x41
1
0x01: Server
0x02: Client
0x02
Sets the mode type. Each network has one
and only one server and any number of
clients. The server is responsible for
transmitting beacons, which are used by
the clients to locate and synchronize their
hopping to that of the server.

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Parameters
EEPROM
Address
Length
(Bytes)
Range
Default
Description
Baud Rate
0x42
1
0x00-0x0A,
0xE3
0x09
Baud Rate, see Serial Interface section for
details. Default represents 115,200 kbps.
Setting this address to 0xE3 allows the user
to set a custom baud rate with the Baud_M
and Baud_E registers.
Baud_M
0x43
1
0x00-0xFF
0x00
Baud_M is used for setting custom baud
rate, see Serial Interface Baud Rate section
for more details.
Baud_E
0x44
1
0x00-0xFF
0x02
Baud_E is used for setting custom baud
rate, see Serial Interface Baud Rate section
for more details.
Control 0
0x45
1
Bit Adjustable
0x88
Settings are:
bit-7: Reserved. Do not modify
bit-6: Sleep Indicator: GIO_1
0 = Disable Sleep Indicator
1 = Enable Sleep Indicator
bit-5: Reserved. Do not modify
bit-4: Auto System ID
0 = Disable Auto System ID
1 = Enable Auto System ID
bit-3: Command/Data Receive Disable
0 = Disable CMD/Data RX Disable
1 = Enable CMD/Data RX Disable (radio
accumulates received RF packets
until the CMD/Data pin goes high, at
which time it forwards all stored
packets to its host).
bit-2: Legacy RSSI
0 = Disable Legacy RSSI
1 = Enable Legacy RSSI
bit-1: Sniff Report
0 = Discard sniffed packets
1 = Report sniffed packets
bit-0: Sniff Permit
0 = Disable Sniff Permit
1 = Enable Sniff Permit
Transmit
Retries
0x4C
1
0x01-0xFF
0x03
Maximum number of times a packet is
retransmitted when Addressed packets are
being sent.
Note: A setting of 0x00 will select 256
retries.
Broadcast
Attempts
0x4D
1
0x01-0xFF
0x03
Number of times each packet is
transmitted when Broadcast packets are
being sent.
Note: A setting of 0x00 selects 256
attempts.