How to transmit data using a cheap RF module through USB. The circuit receives energy from the USB port (may provide 100mA and with some programming you can reach 500mA)
List of Materials:
1 - One pair of RF module (like Laipac RLP/TLP433A) look after it in sparkfun.com (they have different operating frequencies: 315, 433 and 917(?) MHz)
1 - TSUB3410 - Serial-to-USB integrated chip (QFP-32) from Texas Instruments.
1 - One Power LED (you may skip it)
1 - 3.3V LDO (Low Drop-out) regulator - to connect in the +5V (+/- 10%) line from the USB.
Start with the "walkthrough.pdf" guide, after it we will improve the wireless link to be connected to an USB port.
! ! ! - Altought it may look like a very simple circuit (just the RF link), you may find some rocks in your pathway.
I still don't know if this is a reliable circuit..so be carefull where you are going to use it. Be advised to try this circuit ONLY when you are in a good mood! if not go play PS2...otherwise this can damage your parasympathetic nervous system!
Step 1: Checking RF Modules
It´s a good idea to check first the modules. Do it on a breadboard, it works? Fine, move to the next step... or check connections, wires, supply (did you turn it on?).
You can check the wireless link with an osciloscope or using any (hyper) terminal software. Check the maximum baud rate! (mine 4800bps). You may need a MAX232 chip, it is a Serial level converter...
[ PC >> MAX232 >> TX ] ~~~~~~~ air ~~~~~~~~ [ RX >> MAX232 >> PC ]
email me...may be I can help you!