RFDesign RFD900x User manual

www.rfdesign.com.au
Point-to-Point/SIK Firmware
User Manual
For use on the RFD900x/ux/ux-SMT and RFD868x/ux/ux-SMT
Features
• Out of the box RF communications.
• User settable data rates
• Diversity antenna support

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Table of contents
1 Introduction..................................................................................................................................... 4
2 Peer-to-peer Network......................................................................................................................5
3 Software/GCS Support.....................................................................................................................6
4 Configuration of Settings................................................................................................................. 7
4.1 GUI........................................................................................................................................... 7
4.2 AT Commands.......................................................................................................................... 8
4.3 AT Commands Examples........................................................................................................ 14
5 Region Certified Modems.............................................................................................................. 16
5.1 Frequency band example.......................................................................................................16
6 Certifications..................................................................................................................................17
7 Useful links.....................................................................................................................................18
8 Document revision history.............................................................................................................19

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1 Introduction
The RFD900x/ux/ux-SMT and RFD868x/ux/ux-SMT can be loaded with three official firmware
releases to achieve different communication architectures and node topologies.
Available firmware types are:
Point-to-Point/SiK
Asynchronous mesh
Multipoint network
This document describes the configuration of the Point-to-Point/SiK V3.x and up. Modems sold after
April 2019 come with a 3.xx version loaded by default. The firmware has a set of default settings that
allow it to work out of the box in most cases. The firmware will not necessarily be compatible
between versions so it is recommended to update all modems to the same version.

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2 Peer-to-peer Network
The peer-to-peer firmware offers straight forward data communication between two nodes. Figure
4-2 depicts this very simple communication topology. Whenever two nodes have compatible
parameters and are within range, communication will be established after the units synchronise. A
solid green LED state indicates synchronisation has been successful.
Node 1
Node 2
Nodes within range
Figure 4-2: Simple pair mode
If operating with other RFD modems on the same band, you will need to set different network ID’s to
each pair to distinguish the networks from each other. It is also advisable when possible to set the
different pairs on different frequencies. This reduces packet collision, communication instability and
other interference that may reduce the effectiveness of the links.
Given the spectral proximity between the upper and lower bands, enough physical separation is
required to operate radios communicating in separate bands without interference. Users must
ensure the power output setting and antenna configuration are suitable for their regulations and
application prior to deployment.

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3 Software/GCS Support
This firmware is a development of the open source project called “SiK” that was created by Mike
Smith and further developed and modified by Andrew Tridgell and RFDesign.
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”)
Parameters such as power levels, air data rates, serial speeds, GPIO pins etc can all be custom set by
using the AT Command set, the RFD Modem Tools and APM Planner.
Default serial port settings are as follows:
• 57600 baud
• No parity
• 8 data bits
• 1 stop bit
The Point-to-Point/SiK firmware has many software features including:
• Frequency Hopping Spread Spectrum
• Transparent Serial Link
• Configuration by AT commands for local radio, RT commands for remote radio
• User configurable serial data rates and air data rates
• Up to 256 bit AES hardware encryption with user settable key
• 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
• PPM or SBUS (R/C signal) pass through (Control vehicle across radio).
• GIPO pin mirroring
• External lock LED mirror

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4 Configuration of Settings
The RFD x and ux series modems can be configured in two main ways. The use of a GUI tool and
using AT modem commands by serial terminal.
4.1 GUI
There are a number of graphical ways to modify the settings of x series modems using the peer to
peer firmware including the SiK Radio tab under Optional Hardware in Mission Planner and the
RFD900 Tools available from the RFD website (see useful links). This section will provide a very brief
outline of the use of the RFD900 Tools for more information please read the user manual (see useful
links).
Figure 3-1 RFD900 Tools main screen
The COM or network port that the modem is connected to along with the connection rate can be set
in the top right of the screen.
Pressing connect opens the port.
Pressing load settings will connect to the modem and populate the screen with the current settings
of the modem/s.
Settings can be changed using the check and drop-down boxes.
Save settings saves changes made to the modem/s.
Reset to default will apply default settings to the modem/s.
Upload firmware provides a way for the user to update firmware or load an alternative firmware type.

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4.2 AT Commands
The AT command mode can be entered by using the ‘+++’, without quotes, sequence in a serial
terminal connected to the radio.
You should allow at least one second after the sending of data before entering the sequence to
ensure that the modem will correctly enter command mode.
If successful, an ‘OK’ prompt will be displayed on the screen and the modem will stop displaying
incoming data from the remote modem. In command mode, you can use the AT commands to
control the local modem settings 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 value to assign.
2. Use the command AT&W to save the new values to the x and ux series modem.
3. Use the command ATZ to software reboot the modem, required for some changes to take effect.
By replacing A with R the settings of the remote modem can be changed. It is recommended that
changes to remote settings be made first as some of the changes can unlink the modems after being
applied.
AT Command
Description
ATI
Shows the firmware version and country code
ATI1
Shows the firmware version number
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
Calibration validation test
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&R
Record default PPM stream for PPM output (vehicle side)
AT&T
Disables debugging report
AT&T=RSSI
Enables RSSI debugging report
AT&T=TDM
Enables TDM debugging report

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AT Command
Description
AT&E=X
Set new encryption key in hexadecimal characters(e.g. 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)
ATPR=X
Shows GPIO input state
ATPC=X,S
Sets output GPIO X to state S
Table 4-1: AT Commands and their description
An example that command will return the local modem’s firmware version string.
ATI
Response
RFD SiK 3.16 on RFD900X R1.3-AU # On a region locked modem
RFD SiK 3.16 on RFD900X R1.3 # On an unlocked modem
Note the letters after the – indicates the modem is locked. The region is indicated by the letters, -AU
Australia, -NZ New Zealand, -US United States of America and Canada, -EU European Union and -IN
India.
Issuing a AT command will take affect only in the local node. A reset ATZ may be required before the
changes will take effect even after a writing the parameters with AT&W.
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.
RT Command
Description
RTI
Shows the firmware version and country code
RTI1
Shows the firmware version number
RTI2
Shows the board type
RTI3
Shows board frequency
RTI4
Shows board version
RTI5
Shows all user settable EEPROM parameters and their values
RTI5?
Shows all user settable EEPROM parameters and their possible range
RTI6
Displays TDM timing report
RTI7
Displays RSSI signal report
RTI8
Display Device 64-bit unique ID
RTI9
Calibration validation test
RTO
Exits AT command mode
RTSn?
Displays radio 'S' parameter number ‘n’
RTSn=X
Sets radio 'S' parameter number ‘n’ to ‘X’
RTRn?
Displays radio 'R' parameter number ‘n’
RTRn=X
Sets radio 'R' parameter number ‘n’ to ‘X’
RT Command
Description

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RT Command
Description
RTZ
Reboots the radio
RT&F
Resets all parameters to factory defaults
RT&W
Writes current parameters to EEPROM
RT&UPDATE
Reset and enter boot mode
RT&P
Change TDM phase (debug only)
RT&R
Record default PPM stream for PPM output (vehicle side)
RT&T
Disables debugging report
RT&T=RSSI
Enables RSSI debugging report
RT&T=TDM
Enables TDM debugging report
RT&E=X
Set new encryption key (128-bit AES in 16 hex bytes e.g. 5A02D5BB...)
RT&E?
Shows current encryption key
RTPP
Shows GPIO configuration and state
RTPO=X
Sets GPIO X to output
RTPI=X
Sets GPIO X to input
RTPM=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
Shows GPIO input state
RTPC=X,S
Sets output GPIO X to state S
Figure 4-2: RT Commands and their description
Issuing a RT command will take affect only in the remote node. A reset RTZ may be required before
the changes will take effect even after a writing the parameters with RT&W. Link may be lost due to
mismatch in parameter until local settings match the remote node.
S parameters represent the configurable modem settings. These allow the user to configure modem
behaviour to suit their needs.
Note: Some parameters must be the same on both modems in the pair for correct operation.
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. It is set by the firmware
Firmware
dependant
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 and 1000 corresponding to 1200bps,
2400bps, 4800bps, 9600bps, 19200bps,
38400bps, 57600bps, 115200bps,
230400bps, 460800bps and 1000000bps
respectively.
57
1000
1
No
S2
AIR_SPEED1
Air data rate in ‘one-byte form’.
Accepted values14 are 12, 56, 64, 100,
125, 188, 200, 224, 500 and 750
corresponding to value times 1000 bps
e.g. 12000bps, 56000bps etc.
respectively.
64/2004,8
750
12
Yes

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Reg
#
S Register
Description
Default
Value
Maximum
Value
Minimum
Value
Must be the same
at both ends of
the link?
S3
NETID
Network ID.
25
255
0
Yes
S4
TXPOWER1
Transmit power in dBm.
30
30
0
No
S5
ECC2
Enables or disables the Golay error
correcting code.
0
1
0
Yes
S6
MAVLINK3
Enables or disables the MAVLink framing
and reporting
1
1
0
No
S7
OP_RESEND
Opportunistic resend allows the node to
resend packets if it has spare bandwidth
0
1
0
No
S8
MIN_FREQ1
Min frequency in KHz
915000
/8680004,8
927000
/8700004
902000
/8650004,8
Yes
S9
MAX_FREQ1
Max frequency in KHz
928000
/8700004
928000
/8700004
903000
/8650004,8
Yes
S10
NUM_CHANNELS1
Number of frequency hopping channels
20/14,8
518/84,8
1
Yes
S11
DUTY_CYCLE1
The percentage of time to allow transmit
100
100
10
No
S12
LBT_RSSI1
Listen before talk threshold
0
220
25
Yes
S13
RTSCTS
Ready-to-send and Clear-to-send flow
control.
0
1
0
No
S14
Max Window
Max transit window size used to limit
max time/latency can limit throughput
131
400
20
Yes
S15
Encryption Level
Encryption level 0=off, 1=128bit AES,
2=256bit AES8
0
1/28
0
Yes
S16
GPIO1.1 R/C input
Set GPIO 1.1 (pin 15 x/4 ux/22 ux-SMT)
as R/C(PPM) input
0
1
0
No
S17
GPIO1.1 R/C output
Set GPIO 1.1 (pin 15 x/4 ux/22 ux-SMT)
as R/C(PPM) output
0
1
0
No
S18
GPIO1.1 SBUS input7,10
Set GPIO 1.1 (pin 15 x/4 ux/22 ux-SMT)
as R/C(SBUS) input
0
1
0
No
S19
GPIO1.1 SBUS output7,10
Set GPIO 1.1 (pin 15 x/4 ux/22 ux-SMT)
as R/C(SBUS) output
0=Off, 1=SBUS1, 2=SBUS2_12Ch11,
3=SBUS2_18Ch11, 4=SBUS2/111,
5=SBUS1_NOFAIL11
0
5
0
No

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Reg
#
S Register
Description
Default
Value
Maximum
Value
Minimum
Value
Must be the same
at both ends of
the link?
S20
ANT_MODE
0= Diversity, 1= Antenna 1 only, 2=
Antenna 2 only, 3= Antenna 1 TX and
antenna 2 RX
0
3
0
No
S21
GPIO1.3 Status LED output9
Set GPIO 1.3 (pin 12 x/NA ux/24 ux-SMT)
as output with state that mirrors the
status LED on the modem
0
1
0
No
S22
GPIO1.0 485 TX control output6
Set GPIO 1.0 (pin 13 x/NA ux/21 ux-SMT)
as control signal on DINIO and RS485
interface boards.
0
1
0
No
S23
Rate and Frequency Band
Switches between valid settings for the
frequencies, channels and airspeeds that
can be set on compliant modems
ensuring compliance is maintained. See
section 3.4 for FCC-related information.
0
3
0
Yes
S24
GPIO1_2AUXIN12,13
Set GPIO 1.2 (pin 14 x/NA ux/23 ux-SMT)
Auxiliary Serial Input (RX)
0
1
0
No
S25
GPIO_1.3AUXOUT12,13
Set GPIO 1.3 (pin 12 x/NA ux/24 ux-SMT)
Auxiliary Serial Output (TX)
0
1
0
No
S26
Reserved5,12
N/A
N/A
N/A
N/A
S27
Reserved5,12
N/A
N/A
N/A
N/A
S28
FSFRAMELOSS12
Set number of missing frames to trigger
frame time out for SBUS signals
50
5
50
No
R0
TARGET_RSSI
Optimal RSSI value to try to sustain
(255/08disables the feature) V3.09 and
earlier this is based on RSSI figures. After
v3.12 this changes to being based on
receiver dBm
255/08
255/1108
50/08
No
R1
HYSTERESIS_RSSI
Amount of change before power levels
altered. V3.09 and earlier this is based
on RSSI figures. After v3.12 this changes
to being based on receiver dBm
50/58
50/158
20/28
No
Table 4-3: x and ux series parameters
Notes:
1The listed values are the full range of options available on unrestricted modems. The range of settings available may be altered on
compliant systems to maintain compliance to the appropriate standards
2ECC - Software Detection and correction, extra packet information, twice the packet length, is sent to allow the recovery of corrupted
packets. Disabled in version 3.15 and up. Error detection is handled by CRC since at least version 3.01 and may cause data errors.
3Injects RSSI packet when MAVLink protocol used and heartbeat packet detected.

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4868 modems
5Experimental feature settings not currently available
6This setting controls modem functionality linked with 485 interface and DINIO products it is not intended for use outside of this
application.
7Version 3.09 the SBUS function is mapped to GPIO1.3
8Version 3.15 and up
9Pin should be connected to LED cathode and anode connected to power rail should by a resistor to limit maximum current of 5mA
10 Only SBUS channel data is sent over the modem link extra bits such as failsafe flags are not sent. This is to allow for conversion between
signal types over the modem link.
11 SBUS2 as implemented on the RFD modems is not a bidirectional link
12Version 3.20 and up
13Only available on x and ux-SMT
14Available values can vary between modem versions. Certified modems may have further restrictions on accepted values.

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4.3 AT Commands Examples
Encryption
The 128/256 bit AES data encryption may be set, enabled or disabled using the AT commands (see
Table 4.1). The encryption key can be any 32/64 character hexadecimal string.
First enter AT command mode by typing ‘+++’ and waiting for a moment till an ‘OK’ from the modem.
Then to activate encryption on 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 32/64
character hexadecimal string of the users choosing. Any devices with different encryption settings
will not be able to properly decode data.
ATS15=1
AT&E=5AEEF103125C0AA233678909160111CA
AT&W
ATZ
Airdata rate
Reducing the air speed can help to increase the range and link quality limits the data throughput.
Considerations for the air speed setting:
• The desired range
• The amount of data across the link
• Whether you send data in one direction or both
• Whether you have enabled flow control on the serial link
It is important to note that the air rate should be set to a higher value then the baud rate to prevent
bottlenecking and data loss.
Example of changing air data rate:
ATS2=224
AT&W
ATZ

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PPM
To enable PPM control signal pass through on a modem link it is necessary to set the ground station
modem to PPM input and the receiver modem to PPM output. This is enabled using the S registers
16 or 17. The PPM stream can then be injected/retrieved from GPIO1 (aka P1.1 or pin 15) the right
most pin on the bottom row of the header.
Input modem configuration AT commands:
ATPI=1
ATS16=1
AT&W
ATZ
Output modem configuration:
ATPO=1
ATS17=1
AT&W
ATZ
To record a failsafe PPM stream first connect the PPM generator to the ground station modem. Then
power up the receiving modem. Connect the ground station modem using the FTDI cable. After the
modems have established a link set the desired PPM failsafe stream using the generator and connect
to the ground station modem. Then send the following command to set the failsafe on the output
modem.
RT&R
RT&W
RTZ
This could alternatively be done by powering up the ground station and sending the PPM while
connected to the output modem via the FTDI cable in which case the command would be.
AT&R
AT&W
ATZ
Note: It is the the RC output modem that must record the failsafe mode.
Note: Different RC signal types can be inter-converted by the modem. e.g SBUS2_12CH input can be
output as SBUS2_18CH etc.

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5 Region Certified Modems
A modem restricted to regional certified settings will be set at the factory. The country setting cannot
be modified or removed after the modem release. By the same token an unlocked modem cannot be
set with country compliance after the modem release. Modems with country settings cannot be
loaded with all firmware versions including some prior to the SiK versions. Unlocked modems can be
loaded with all firmware version. Any 900x modems sold before the release of certified modems
operate as an unlocked modem.
5.1 Frequency band example
FCC-compliant radios, designated as RFD900x-US, are allowed to operate in two different frequency
bands. The user might operate two pairs of radio simultaneously without them interfering with each
other – given a minimal physical distance between the radios is respected – while remaining FCC-
compliant by setting each pair to a different frequency band. This can be achieved by setting the S23
parameter according to the table below.
S23 value
Description
Minimum
frequency
Maximum
Frequency
Number of
channels
0
Lower frequency band
902.125 MHz
914.875 MHz
51
1
Upper frequency band
915.125 MHz
927.875 MHz
51
When operating multiple sets of modems with frequency separation, e.g. upper and lower bands,
physical separation is required between modems to minimise interference. Users must ensure the
power output setting and antenna configuration are suitable for their application prior to
deployment.
Airspeed on FCC-compliant radios are limited to 12, 64, 125 and 224kbps as to meet FCC
requirements. The airspeed is still set using the S1 parameter.

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6 Certifications
Compliance
AS/NZS 4268:2012
FCC 47CFR 15.247
FCC 47CFR Part 1.1307
FCC 47CFR 1.1310
IC RSS247
EN 300200
EN62311
EN301489
865-867MHz unlicensed band in India
Note: Applicable certifications apply to certified modem versions.

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7 Useful links
RDF900x/RFD868x modem Firmware
The firmware is the same for both the 868x/900x modems and can be found at.
http://files.rfdesign.com.au/firmware/
RFD TOOLS
http://files.rfdesign.com.au/tools/
Documentation (including FAQ)
http://files.rfdesign.com.au/docs/
Store
http://store.rfdesign.com.au
FTDI Cable documentation
http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf

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8 Document revision history
Version
Date
Changes
1.0
19/03/19
Release document
1.1
24/09/19
1.2
16/03/20
Added section 3.4
1.3
03/04/20
Updated for changes in v3.15 firmware
1.4
17/12/20
Updated for changes in v3.20 firmware and general amendments