TX module heating up ????

[mackrackit]

Mr Google gave this
http://dave.fraildream.net/micro/periph/232-ttl.html
but it is not me.

[Bruce]

The same circuit I already drew-up for you works on both ends. Your RF receiver data output pin would connect to the base of the PNP transistor labeled USART, and the PIC USART RX input pin would connect to the PNP collector/resistor node labeled RF TX.

The logic on the PIC USART RX input pin should idle high. With the RF receiver output idling LOW, that's exactly what you'll have on the PIC USART RX input with this same PNP inverter circuit.

It's just basic electronics...

[Megahertz]

I am sorry , I am on a very steep learning curve here. Just want to confirm that if there is any resistance needed between base and USART or direct connection is fine? Thanks

[Bruce]

You can get by without the base resistor. If you will be flipping power on/off a lot, and want to make sure the transistor stays off until it's turned on, you can use an inverter circuit like this one http://www.rentron.com/IRTORF_TX.gif

The 10K pull-up holds the base at logic 1 keeping the transistor off while the PIC powers up. If it's battery operated a small FET would be a better choice than a transistor.

I drew another quick schematic for you. Either receiver inverter will work, but the NPN circuit would be best.