RFDesign RFD900 Series User manual

www.rfdesign.com.au
Last update 06/12/2016
RFD900x Multipoint firmware
User Manual
Configuration and usage guide
Flash Programmer User Manual

RFD900x Data Sheet
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RFDesign Pty Ltd
7/1 Stockwell Place
Archerfield, QLD 4108
rfdesign.com.au
Table of contents
Table of contents ....................................................................................................................................1
1 Introduction ....................................................................................................................................2
2 Software/GCS Support....................................................................................................................3
3 AT commands..................................................................................................................................4
3.1 Setting up data encryption .....................................................................................................8
3.2 Setting the air data rate..........................................................................................................8
4 Multipoint Network ........................................................................................................................9
5 Frequently asked questions (FAQ)................................................................................................12
How many antennas do I need to use? ............................................................................................13
How do I connect the FTDI cable to the modem? ............................................................................13
What do I need to upload the firmware or to change the modem configuration?..........................13
What should I do if the Flash Programmer keeps displaying error messages? ................................13
I upgraded to multipoint firmware and the modems don't connect anymore? ..............................13
6 Useful links....................................................................................................................................14
1 Document revision history............................................................................................................15

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1Introduction
The RFD900x radio modem can be loaded with three official firmware releases to achieve different
communication architectures and node topologies. So far, the available firmware versions are:
•Peer-to-peer (P2P)
•Multipoint network
•Asynchronous mesh
This document describes the configuration of the Multipoint network release. This firmware version
is not loaded in the RFD900x radio modem by default. This means, you must download it from the
website and flash it to the radio. The download link can be found in section “Useful links”.
The modems feature a boot loader to facilitate field upgrade of the modem firmware via the serial
port. This is most easily performed by using the latest version RFD Modem tools (see “Useful links”)
Figure 1-1 pictures a generic multipoint network. The network requires that one of the devices
assumes a master role to control the timeslot distribution of the surrounding radios.
Figure 1-1: Multipoint network architecture
As depicted in Figure 1-1, the multipoint network allows each node to be addressed individually.
However, after receiving data it is not possible to identify which node it came from.
Note: Due to the limited number of channels available on the 868 MHz band this firmware may not
operate as intended and is not recommended for 868X modems or reduced band settings less than
915-928MHz on 900X modems
Note: For more reliable operation use of flow control is recommended.
Node 2
Node 3
Node 4
Node 1
Master
Within master node
range

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2Software/GCS Support
The Multipoint network firmware is currently only configurable using AT Commands support for
managing settings using the RFD tools may be added later.
Default serial port settings are as follows:
•57600 baud rate
•No parity
•8 data bits
•1 stop bit
The RFD900x Radio Modem has many software features including:
•Frequency Hopping Spread Spectrum
•Transparent Serial Link
•Configuration by simple AT commands for local radio, RT Commands for remote radio
•User configurable serial data rates and air data rates
•Error correction routines, MAVLink protocol framing (user selectable)
•MAVLink radio status reporting (Local RSSI, Remote RSSI, Local Noise, Remote Noise)
•Automatic antenna diversity switching on a packet basis in real-time
•Automatic duty cycle throttling based on radio temperature to avoid overheating

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3AT commands
The RFD900x modem can support the Hayes ‘AT’ modem command set for configuration. The AT
command mode can be entered by using the ‘+++’ sequence in a serial terminal connected to the
radio. When doing this, you must allow at least 1 second after any data is sent to be ensure the request
for command mode is not interpreted as data. When you are successfully in the AT command mode,
an ‘OK’ prompt will be displayed on the screen and the RFD900x modem will stop displaying incoming
data from the remote modem. Whilst in command mode, you can use the AT commands to control
the local RFD900x modem or the RT commands to control the remote modem.
To set certain registers to a value, follow these steps:
1. Use the command ATSn=X where nis the register number and Xis the actual value.
2. Use the command AT&W to save the new values to the RFD900x modem.
3. Use the command ATZ to reboot the RFD900x modem for changes to take effect.
Table 3-1 shows a gives a list of AT commands and their description.
AT Command
Description
ATI
Shows the radio version
ATI2
Shows the board type
ATI3
Shows board frequency
ATI4
Shows board version
ATI5
Shows all user settable EEPROM parameters and their values
ATI5?
Shows all user settable EEPROM parameters and their possible range
ATI6
Displays TDM timing report
ATI7
Displays RSSI signal report
ATI8
Display Device 64-bit unique ID
ATI9
Display node ID [multipoint only]
ATO
Exits AT command mode
ATSn?
Displays radio 'S' parameter number ‘n’
ATSn=X
Sets radio 'S' parameter number ‘n’ to ‘X’
ATRn?
Displays radio 'R' parameter number ‘n’
ATRn=X
Sets radio 'R' parameter number ‘n’ to ‘X’
ATZ
Reboots the radio
AT&F
Resets all parameters to factory defaults
AT&W
Writes current parameters to EEPROM
AT&UPDATE
Reset and enter boot mode
AT&P
Change TDM phase (debug only)
AT&T
Disables debugging report
AT&T=RSSI
Enables RSSI debugging report
AT&T=TDM
Enables TDM debugging report
AT&E=X
Set new encryption key (128-bit AES in 16 hex bytes 5A02D5BB...)
AT&E?
Shows current encryption key
ATPP
Shows GPIO configuration and state
ATPO=X
Sets GPIO X to output
ATPI=X
Sets GPIO X to input
ATPM=X
Sets input GPIO pin to mirror on remote radio (local GPIO must be set to input
and remote GPIO pin must be set to output)

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ATPR=X
Shows GPIO input state
ATPC=X,S
Sets output GPIO X to state S
AT&M?
Current master node settings
AT&MX=A,B
Describes the network configuration. Only set this on master node(NETID=0,
NODEID=1). X is the network number (note must start with 0 as this is the
synchronising network). A is the start channel ID of the network (this also starts
at 0 and can have values 0,7 or 13). B is the nodecount of the network (i.e. the
number of nodes on the network including the master)
Table 3-1: AT Commands and their description
RT commands are terminal commands that take effect on a remote node. They allow the user to set
or get a remote node’s parameter, for instance, as if they were being set locally. Table 10-2 lists the
RT commands and their respective descriptions.
RT Command
Description
RTI,[x]
Shows the radio version
RTI2,[x]
Shows the board type
RTI3,[x]
Shows board frequency
RTI4,[x]
Shows board version
RTI5,[x]
Shows all user settable EEPROM parameters and their values
RTI5?,[x]
Shows all user settable EEPROM parameters and their possible range
RTI6,[x]
Displays TDM timing report
RTI7,[x]
Displays RSSI signal report
RTI8,[x]
Display Device 64-bit unique ID
RTI9,[x]
Display node ID [multipoint only]
RTO,[x]
Exits AT command mode
RTSn?,[x]
Displays radio 'S' parameter number ‘n’
RTSn=X,[x]
Sets radio 'S' parameter number ‘n’ to ‘X’
RTRn?,[x]
Displays radio 'R' parameter number ‘n’
RTRn=X,[x]
Sets radio 'R' parameter number ‘n’ to ‘X’
RTZ,[x]
Reboots the radio
RT&F,[x]
Resets all parameters to factory defaults
RT&W,[x]
Writes current parameters to EEPROM
RT&UPDATE,[x]
Reset and enter boot mode
RT&P,[x]
Change TDM phase (debug only)
RT&T,[x]
Disables debugging report
RT&T=RSSI,[x]
Enables RSSI debugging report
RT&T=TDM,[x]
Enables TDM debugging report
RT&E=X,[x]
Set new encryption key (128-bit AES in 16 hex bytes e.g. 5A02D5BB...)
RT&E?,[x]
Shows current encryption key
RTPP,[x]
Shows GPIO configuration and state
RTPO=X,[x]
Sets GPIO X to output
RTPI=X,[x]
Sets GPIO X to input
RTPM=X,[x]
Sets input GPIO pin to mirror on remote radio (local GPIO must be set to input
and remote GPIO pin must be set to output)
RTPR=X,[x]
Shows GPIO input state
RTPC=X,S,[x]
Sets output GPIO X to state S
Figure 3-2: RT Commands and their description

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Issuing a RT, command will take effect only in the remote node in a peer-to-peer configuration, which
if a very useful feature if you have a remote node that is hard to access. Just make sure to keep the
parameters compatible, whenever changing a parameter in the remote node.
RT commands on multipoint network will solicit a response from all available nodes on the network
unless addressed to an individual node. This can be done by setting the destination ID of the sending
node to match the desired node or by appending ,[x] to the RT command as per the examples below.
This example describes how to get the radio version of the remote node 1 in a multipoint network
(append,[x] where x is desired node to RTI command):
RTI,1
If the local parameter NODEDESTINATION (refer to table 3-3 for parameter usage and description) is
already set to 1, the following RT command will also retrieve the remote node’s version number:
RTI
Table 3-3 shows more details about the parameters that can be set in the RFD900x modem.
Reg
#
S Register
Description
Default
Value
Maximum
Value
Minimum
Value
Must be the same
at both ends of
the link?
S0
FORMAT
This is for EEPROM version, it should not
be changed
69
N/A
N/A
No
S1
SERIAL_SPEED
Serial speed in ‘one-byte form’. Accepted
values are 1, 2, 4, 9, 19, 38, 57, 115, 230,
460,1000 corresponding to 1200bps,
2400bps, 4800bps, 9600bps, 19200bps,
38400bps, 57600bps, 115200bps,
230400bps, 460800bps, and 1000000bps
respectively.
57
460
1
No
S2
AIR_SPEED
Air data rate in one-byte form
64
250
12
Yes
S3
NETID
Network ID. It should be the same on all
modems of the network
0
7,131
0
Yes
S4
TXPOWER
Transmit power in dBm. Maximum is
30dBm
27
30
0
No
S5
ECC2
Enables or disables the Golay error
correcting code. When enabled, it doubles
the over-the-air data usage
0
1
0
Yes
S6
RXFRAME
Sets the data type for the modem. 0=Raw,
1=Mavlink3, 2 = SAS
1
2
0
No
S7
OP_RESEND4
Deprecated. Has no effect.
0
0
0
No

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S8
MIN_FREQ
Min frequency in KHz
915000
927000
902000
Yes
S9
MAX_FREQ
Max frequency in KHz
928000
928000
903000
Yes
S10
NUM_CHANNELS
Number of frequency hopping channels.
Do not change as this will affect the
spectrum separation of the nodes
21
50
1
Yes
S11
DUTY_CYCLE
The percentage of time to allow transmit
100
100
10
No
S12
LBT_RSSI
Listen before talk threshold
(This parameter shouldn’t be changed)
0
220
25
Yes
S13
RTSCTS
Ready-to-send and Clear-to-send.
0
1
0
No
S14
Max Window
Max transit window size used to limit max
time/latency if required otherwise will be
set automatically
80
400
20
Yes
S15
Encryption Level
Encryption level 0=off, 1=128bit
0
1
0
Yes
S16
ANT Mode
Set antenna port function. 0= Diversity,
1=A1 only, 2=A2 only, 3= A1 TX and A2 RX
0
3
0
No
S17
STATUS GPIO1.3
Set GPIO 1.3 to behave the same as the
status LED allowing link lock status to read
from the I/O pin
0
1
0
No
S18
NODEID
Node ID. One node must be acting as a
master (NODEID 1, NETID 0) for a
multipoint environment to work.
2
15
1
N/A
S19
NODEDESTINATION
Remote node ID to communicate with. Set
the value to 255 to broadcast to all nodes.
Cannot be the same as NODEID.
255
255
1
No
S20
NETCOUNT
The total number of networks on the one
master node. Not applicable to non-
master nodes.
1
105
1
Yes
S21
SERBREAKDETECTMS10
x10 to give time in ms units for break
detection. Set to 0 to turn this feature off
0
20
0
No
R0
TARGET_RSSI
Optimal RSSI value to try to sustain (255
disables the feature)
255
50
255
No
R1
HYSTERESIS_RSSI
Amount of change before power levels
altered
50
20
50
No
Table 3-3: RFD900x parameters

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Notes:
1To ensure the correct channel separation between networks this should only take the values 0,7 or 13
2ECC - Software Detection and correction, extra packet information, twice the packet length, is sent to allow the recovery of corrupted
packets. This increases the data usage of the link.
3Injects RSSI packet when MAVLink protocol used and heartbeat packet detected.
4Opportunistic resend allows the node to resend packets if it has spare bandwidth.
5Not recommended to use more then 3 networks as there may not be enough channel separation to prevent interference between modems
3.1 Setting up data encryption
The 128-bit AES data encryption may be set, enabled and disabled using the AT commands (see Table
2.1). The encryption key can be any 32-character hexadecimal string. Data encryption is essential for
the separation of different networks.
To encrypt a device, the encryption mode must first be enabled by typing ‘ATS15=1’ in the command
terminal. Once the encryption mode is active, an encryption key may be set after typing ‘AT&E’ into
the command terminal. The encryption key may be of any 32-character hexadecimal string of the users
choosing. Any devices with different encryption settings will not communicate.
After entering command mode, send the following commands to set encryption on using an arbitrary
16-byte key:
ATS15=1
AT&E=5AEEF103125C0AA233678909160111CA
AT&W
ATZ
3.2 Setting the air data rate
An air speed of 64kps will allow for 3 networks of 4 nodes. If the air speed is set to be lower, the range
of the wireless link increases but the amount of data that you can send will be limited and the number
of nodes that can be supported will also decrease. If set higher the greater throughput allows for more
nodes but reduces range.
The air data rate is chosen depending on:
•The range that you need
•How many nodes you want on each network
•The data rate that you will be sending
•Whether you send data in one direction or both
•Whether you have enabled ECC or not
•Whether you have APM firmware with adaptive flow control
It is important to note that the board’s data rate must be set to a higher value then the air data rate
(when flow control is enabled) to prevent bottlenecking and data loss.
To set a 250kbps air data rate, for instance, enter command mode and issue:
ATS2=250
AT&W
ATZ

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4Multipoint Network
The multipoint mode requires the firmware to be loaded into the all network radios. Check section
“Useful links” for the download link and refer to section “RFD900x Flash Programmer tool” to flash
the multipoint firmware. After flashing the device, you are required to choose a master node that will
control the radio timeslot allocations.
Figure 4-2: multipoint network diagram example
At this time the multipoint firmware settings are not supported by the RFD modem tools. Therefore,
all settings must be made by AT commands via a terminal programme. The list of AT commands can
be found in section three of this manual.
To set up the multipoint network, each device must be assigned a unique Node ID on its network. A
device set as master is also mandatory.
By default, the nodes are configured to address all the other nodes in broadcast mode. To address a
specific node, you must set the Node Destination parameter. For example, to address the data to node
1, you must send the following commands in command mode:
ATS19=1
AT&W
ATZ
A few notes on the multipoint network (see Figure 1-2):
•Based on the topology depicted in Figure 1-2, for Node 3 to communicate with Node 2, Node 1
(the base) and Node 2 must be within the RF range, and
•More nodes will reduce the bandwidth.
4.1 Example network configurations
This section will cover the modem settings for some of the network types that may be desired. As a
general rule lower airspeed will allow for more range but limit the amount of data that can be
transferred.
Node 2
Node 3
Node 4
Node 1
Master
Within master node
range