Small TX/RX
Radio Modules
Tests with PICAXE & PIC
d. bodnar revised 04-25-15
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.
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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
start:
Temp2=Temp2+1
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: http://melabs.com/resources/pbpmanual/)
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
start:
Temp2=Temp2+1
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: https://www.pjrc.com/teensy/td_libs_VirtualWire.html
Update - BangGood TX/RX pair
I repeated the above tests with a set of units from Banggood (see:
http://us.banggood.com/Wholesale-Warehouse-3400-Radio-Receiver-Module-433RF-Wireless-Transmitter-Module-wp-Usa-970238.html
)
The work well and are compatible with the $1.00 transmitter - nice!