In another thread the DORJI RF Transceiver Modules were brought up. So I decided to order a pair for testing
and evaluation.
I got the 7020D20 modules that can be programmed for an output up to 20dBm (100mW). This is over the
allowable output in most countries so be sure program the modules for 13dBm to be compliant. If you get
these be sure to get at least one of the USB adapters to allow use of the Configuration
Utility.
What I discovered was a lack of good documentation. The "datasheet" only covers configuration of the module
and offers nothing on how to actually use them.
Usage is fairly simple. Set the EN Pin high and what you send to the rx pin gets transmitted on air AFTER it sees
a <CR>,<LF> sequence. The <cr> ,<LF> is transmitted along with whatever was in the buffer.
A receiver set to the same frequency receives the data packet and sends it out its TX Pin.
When data is being received, the AUX Pin toggles high for the duration of the data packet. This signal can be
used to trigger an interrupt on the Picaxe to tell it to process data received. Very useful when using
the hserin PIN and background receive.
I have written Picaxe specific code that demonstrates the versatility of these module when using a Picaxe 20X2.
One Module acts as a Primary TX and sends out a data packet that includes a destination address, 4 data bytes,
and a 16 bit CRC.
The other module receives the data, validates the address ( "is this for me?") and checks the CRC. If all is well an
ACK is send back to the Primary TX module. Sertxd data is sent out by both both modules and a terminal will give
visual of what's happening. RX and TX LEDS on both modules also give a visual of data being sent / received.
The code is attached and has been tested to work and should serve to help with understanding how the modules
work and how to reliable transmit data over an RF link with some basic error checking.
These are really really nice modules for personal use and experimentation with a range up to and beyond 1000 meters.
Have Fun !
and evaluation.
I got the 7020D20 modules that can be programmed for an output up to 20dBm (100mW). This is over the
allowable output in most countries so be sure program the modules for 13dBm to be compliant. If you get
these be sure to get at least one of the USB adapters to allow use of the Configuration
Utility.
What I discovered was a lack of good documentation. The "datasheet" only covers configuration of the module
and offers nothing on how to actually use them.
Usage is fairly simple. Set the EN Pin high and what you send to the rx pin gets transmitted on air
a <CR>,<LF> sequence. The <cr> ,<LF> is transmitted along with whatever was in the buffer.
A receiver set to the same frequency receives the data packet and sends it out its TX Pin.
When data is being received, the AUX Pin toggles high for the duration of the data packet. This signal can be
used to trigger an interrupt on the Picaxe to tell it to process data received. Very useful when using
the hserin PIN and background receive.
I have written Picaxe specific code that demonstrates the versatility of these module when using a Picaxe 20X2.
One Module acts as a Primary TX and sends out a data packet that includes a destination address, 4 data bytes,
and a 16 bit CRC.
The other module receives the data, validates the address ( "is this for me?") and checks the CRC. If all is well an
ACK is send back to the Primary TX module. Sertxd data is sent out by both both modules and a terminal will give
visual of what's happening. RX and TX LEDS on both modules also give a visual of data being sent / received.
The code is attached and has been tested to work and should serve to help with understanding how the modules
work and how to reliable transmit data over an RF link with some basic error checking.
These are really really nice modules for personal use and experimentation with a range up to and beyond 1000 meters.
Have Fun !
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