RF decoding with PIC

[Spectacular Butter]

Hi, just wanted to get some concepts right before i proceed.

I am planning on using a PIC microcontroller. When the receiver receives the RF signal, do i feed the received signal to a decoder IC before sending it to the PIC or can the PIC receive the RF signal straight away to decode it to digital form?

Many thanks.

 

[evandude]

microchip makes a line of RFPICs... perhaps those would work well for you...

otherwise i would say definitely use a decoder... even if the PIC could handle the decoding (depending on the RF frequency that will probably not be feasible/possible) it would be better to let the pic handle other things, rather than wasting time with that when a separate IC could handle it

 

[Spectacular Butter]

Hi,

i realise the output of the ADC for PIC controllers is 10 bits. The encoder i plan to use HT12E, is only 4 bit data. Is there anyway to convert the ADC output to 4 bits instead?

 

[Nigel Goodwin]

Hi,

i realise the output of the ADC for PIC controllers is 10 bits. The encoder i plan to use HT12E, is only 4 bit data. Is there anyway to convert the ADC output to 4 bits instead?

The HT12E is a simple remote control encoder (ON or OFF), it's not designed to be fed from a PIC - what are you trying to do?, and why don't you just use the PIC to do the coding?.

 

[Spectacular Butter]

Thanks for replying.

I am trying to establish an RF link with the PIC to control a car using a PC parallel port.

I planned to do it this way:

The 4 inputs from the Parallel port represent (forward, left, right, brake)
The PIC listens for signals from the parallel port at its I/O pins. If a 1 0 0 0 is sent, then the PIC will know it is going forward.

The PC should also be able to monitor the condition of the car battery and temperature. Unfortunately, seems like there is only 8 data pins for the pc parallel port. So the other 4 pins is used for monitoring purposes.

Unfortunately...again, the ADC for the PIC is 10 bits, so i am having trouble sending the info back in 4 bits.

Any advice?

 

[Nigel Goodwin]

Thanks for replying.

I am trying to establish an RF link with the PIC to control a car using a PC parallel port.

I planned to do it this way:

The 4 inputs from the Parallel port represent (forward, left, right, brake)
The PIC listens for signals from the parallel port at its I/O pins. If a 1 0 0 0 is sent, then the PIC will know it is going forward.

The PC should also be able to monitor the condition of the car battery and temperature. Unfortunately, seems like there is only 8 data pins for the pc parallel port. So the other 4 pins is used for monitoring purposes.

Unfortunately...again, the ADC for the PIC is 10 bits, so i am having trouble sending the info back in 4 bits.

Any advice?

This seems rather a waste of four perfectly good Holtek IC's!.

At the PC end the PC can feed the transceiver directly (with software running in the PC), at the remote end a PIC can do everything the Holtek chips do at that end. The Holtek IC's aren't designed for this use at all, but for simple ON/OFF remote control applications - so they are a very poor choice.

The PIC having a 10bit A2D is irrelevent really, if you want to use it as a four bit A2D simply use the top four bits!.

 

[fabbie]

The PIC having a 10bit A2D is irrelevent really, if you want to use it as a four bit A2D simply use the top four bits!.

If a analogue signal is converted into digital, and u happen to only use up the 4 most significant bit of 10bits, wouldnt this affect the accuracy of the cinversion? 4 bits can only produce up to 16 states. How isit possible to monitor a wide temperature range?

 

[Nigel Goodwin]

The PIC having a 10bit A2D is irrelevent really, if you want to use it as a four bit A2D simply use the top four bits!.

If a analogue signal is converted into digital, and u happen to only use up the 4 most significant bit of 10bits, wouldnt this affect the accuracy of the cinversion? 4 bits can only produce up to 16 states. How isit possible to monitor a wide temperature range?

That's exactly right, if you only use 4 bit resolution, you only have 16 possible states. You can still monitor a wide temperature range - but only with really poor resolution - 4 degrees resolution over a 64 degree range.

The entire idea with the Holtek remote encoders is seriously flawed.