Hi,
I've purchased 2 pairs of RF module recently. TLP434A and RLP434 as shown in the attachment. I want to use it as the carrier of my remote control. I'm using a single remote control to control 2 devices. Basically the function is just turning on and off 2 receivers, so I need only 4 different data.
I've referred to Nigel's tutorial 12.3, and I have some question here.
Are the INDF and FSR register working together? It seems their contents are the same. Can I use other defined constant instead of using these?
What is the usage of this: fast CRC-8 algorithm with poly x^8+x^5+x^4+1 executes in 23 cycles per update?
When I bought this RF module, the technician told me that it is good to use the module with the encoder and decoder, as shown in the attachment as well. Any encoder and decoder will work. But I don't think Nigel's and Peter JAKAB's remote control have these encoder or decoder, simply the PIC with the RF module and other application components.
Any idea?

Thanks

Attached Files

TLP434A.pdf (30.7 KB, 191 views)

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bananasiong

 

The PIC does all the coding and decoding, you can send what you want in the data packets - if it's a simple remote control you just need device ID and function - you could use the SIRC's routines from my IR tutorial just as well for remote control via radio.

INDF and FSR are for indirect addressing, consult the PIC datasheet.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

from the transmitter code above, the content of 0xAA is XORed with the content of sum, but what's the content of 0xAA??

THanks

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bananasiong

 

I'm not sure whether the RF module is working or not, because I've connected everything well, Vcc and Vss, when I connect the data input pin to Vcc, the digital output at the receiver is around 2V measured, when I connect the input pin to ground, the output is also 2V.
Should I test with the pulses as input signal?

Thanks

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bananasiong

 

RF modules aren't DC coupled, so you can't just DC switch the input - feed it a 1KHz squarewave and use a scope on the receiver.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Yes, I can see the waveform from the receiver by a scope. But when I use a PIC to input to the transmitter, with 500 Hz (1 ms on and 1 ms off) to send 8 pulses, and there is also a PIC with the receiver to count the received pulses. It responses only when it receives 8 pulses. But it seems not working. Is there any easier way to check the communication between 2 PIC's before I do manchester coding? Do I need to pull up or down the input pin of the PIC via a resistor?

Thanks

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bananasiong

 

Check the circuit my tutorial uses, you don't need a pullup - because it's AC coupled you can't input a long high level - 1mS might be too long, if the waveform out of the receiver the same as that going in the transmitter?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Yes, the waveform into the transmitter and out from the receiver are the same. I've tried with 0.5ms, but it doesn't work as well.

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bananasiong

 

My connections are okay, just according to the datasheet and I don't put any decoupling capacitor like yours. Does it cause the RF module not to work?

Thanks

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bananasiong

 

Any circuit requires decoupling capacitors to help it function properly, you should put capacitors near the power pins on any IC's, and the RF module.

It 'may' work fine without it?, and perhaps has something on the substrate?, but it's good practice to add decouplers!.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Yes I have decoupling capacitor for the PIC, but not the RF module. I'll try it soon.
And, is it okay if I test it on a breadboard? I think it should be fine since the modulation is done on the RF module itself.

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bananasiong

 

The module manufacturers say not even to use stripboard! - never mind breadboard (notice my tutorials have the unused strips removed).

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

My program seems to be very long. According to the datasheet, PIC16F877A has 8K memory, in hex, it is 0x2000. As long as the hex file size is less than 0x2000, my program will work well? Even branch from the very begging line to the very last line has no problem?

Thanks

__________________
bananasiong

 

The PIC 16F series consist of a number of 2K pages, if you goto or gosub to a different page you have to set it accordingly. As long as you stay in the first 2K of memory this isn't a concern - are you sure your program is anywhere near 2K, 2K is a LOT of assembler!.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

A hex file is an ASCII representation of the binary codes using hexadecimal characters, along with address, data type and row check sum included.

Therefore you cannot just look at the HEX file size to determine the actual binary code size. You need to load the hex file into any PIC programming software and then you can examine/view the actual length of your program.

As a rough guess, the HEX file size will be 2.5x or more the actual size of the binary codes.

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L.Chung