Small TX/RX Radio Modules
Tests with PICAXE & PIC

d. bodnar  revised 0

I have been testing an array of inexpensive transmitter / receiver pairs that can be used with PIC, PICAXE and Arduino processors.  This page is just some notes I put together recently.

Part of the PICBasic code is here: 

Include "modedefs.bas"
SerialOut var GPIO.0 'pin 7
serout serialout,n9600,[12,10,13,"Ver 0.1 FireBox",10,13]
serout serialout,n9600,["(c) d. bodnar 05-11-14",10,13]
serout SerialOut,n9600,["@ GetRndRange ",#MinNumber," ",#RndRange]

Gives this on the logic analyzer (note "Get Rnd Range" is decoded)

These settings decode the RS232 - note that the data is "Inverted"

This works, too:

Include "modedefs.bas"
ansel = 0
cmcon0 = 7
Serial_out var gpio.0 'pin 7 'cds photo sensor

Temp2 var word

''''OSCCON = %01110000 ' Set to 8MHz
---REMOVE to run at 9600 - with it baud rate is doubled
Serout serial_out,n9600,[13,10,13,10,13,10,"d. bodnar Ver 4.1 + CDs Morse Board",13,10]
Serout serial_out,n9600,[13,10,"8 MhZ 1-22-13",13,10]

gpio = %00011000 '3 & 4 inputs - others outputs

serout serial_out,n9600,["Temp Variable = ",#Temp2,13,10]

goto start:

This from the scope - 9600 baud - be sure to set polarity as shown (in circle)


I tested the small, $1.00 pairs at 1200 baud and got good range, from the workbench to the far side of the driveway, about 100 feet through a concrete block wall

These can be purchased on eBay and other vendors for as little as $1.00 per pair - search for "315Mhz RF transmitter and receiver"

These also tested well at 2400 baud using both serout and serout2 - see the code section below  - note that the output is inverted (see Appendix A here:

BBaud con 16780' 16780 is 2400 inverted, 
''''OSCCON = %01110000 ' Set to 8MHz
Serout2 serial_out,bbaud,[13,10,13,10,13,10,"d. bodnar Ver 4.1 + CDs Morse Board",13,10]
Serout2 serial_out,bbaud,[13,10,"8 MhZ 1-22-13",13,10]

gpio = %00011000 '3 & 4 inputs - others outputs

serout2 serial_out,bbaud,["Temp Variable = ",#Temp2,13,10]
' pause 2000
goto start:

The devices seem happiest with a continuous stream of data rather than data, pause 1000, data, etc

Good Arduino info here:


Update - BangGood TX/RX pair
I repeated the above tests with a set of units from Banggood (see: )

The work well and are compatible with the $1.00 transmitter - nice!