Serial Data for PIC16LF84A

[oneohthree]

I am only transmitting 4 bits from the transmitter to the receiver. Would manchester encoding be necessary, because from what I read it's not needed.

[skimask]

I am only transmitting 4 bits from the transmitter to the receiver. Would manchester encoding be necessary, because from what I read it's not needed.

Then you didn't read enough of the posts.
Generally speaking, you can't send straight serial data into the transmitter and get that same straight serial data out of the receiver.
As all of those posts said, you have to sync up the receiver by sending sync bytes.
Since you are only sending 4 bits, you encode them at the transmitter end (giving you 8 bits total), and decode that byte at the receiver end (getting back your 4 bits from 8).
But again, as I've stated elsewhere, you're dropping all the way into your project without taking little steps first.
Hook up a couple of LEDs to the RX PIC and get those to flash on command from the TX PIC, anything to prove that you can write the code needed to do the job.
Then work your way up to sending functional data across the RF link to do the job you need.

As to whether or not manchester encoding would be needed?
Maybe not, but your data will be a whole heck of lot more reliable (up to the point of being almost completely unreliable if you didn't encode it) at the receiver end if you implented some sort of coding.

come to think of it, do a search on 'data slicer', will probably give you a bit more info.

[sougata]

Hi,

Without going into much technical blah... blah.. (Which I don't understand )

Skimask please correct me if I am wrong as I have never used a Tx/Rx module.

Your Tx and Rx module uses ASK (amplitude shift keying). This is the most frequent and low cost. It means that your receiver demodulates the signal by finding a difference of the transmitted carrier level. Now take for example that you need to transmit 255 = b'11111111' . For 8N1 you would actually set the output (carrier) high for the start bit and since all of your bits are high through the ending stop bit you would be keeping it high for the entire byte. This is NRZ (Non return to Zero) and drives your receiver nuts and it cannot see a practical shift in the amplitude.

Thus comes manchester to the rescue. It ensures transition for every bit. It is used for automatic clock recovery but here it eases the ASK demodulation.


If you are sending only a specific byte, (if the sending is in your hand) then you can actually use shifting 1s. Guess what you get at the receiver side ? I will leave that for your research

[skimask]

Hi, Without going into much technical blah... blah.. (Which I don't understand ) Skimask please correct me if I am wrong as I have never used a Tx/Rx module. Your Tx and Rx module uses ASK (amplitude shift keying). This is the most frequent and low cost. It means that your receiver demodulates the signal by finding a difference of the transmitted carrier level. Now take for example that you need to transmit 255 = b'11111111' . For 8N1 you would actually set the output (carrier) high for the start bit and since all of your bits are high through the ending stop bit you would be keeping it high for the entire byte. This is NRZ (Non return to Zero) and drives your receiver nuts and it cannot see a practical shift in the amplitude. Thus comes manchester to the rescue. It ensures transition for every bit. It is used for automatic clock recovery but here it eases the ASK demodulation.
Attachment 1499
Attachment 1500
If you are sending only a specific byte, (if the sending is in your hand) then you can actually use shifting 1s. Guess what you get at the receiver side ? I will leave that for your research

Are you asking me a question, trying to tell me something or what?

As long as I've got an equal number of 0's and 1's, I don't care how I get it to work (manchester encoding, lookup/lookdown tables, whatever), as long as it works. Data slicer stays happy, I stay happy...and it works very well. I've got a few sets of the TLP/RLP-434's and a few others from Rentron. Funny thing though, the spec sheets say that they max out at about 2400bps (maybe 4800, I forget). I've been able to use them at 19.2kbps (albiet shorter range) successfully a number of time.

[sougata]

Are you asking me a question, trying to tell me something or what?

Dear Skimask,

I have clearly mentioned that I have never used a Tx/Rx module ever. I tried to explain something which is not practically tested by me. So I was seeking support to correct me if I state something.

[skimask]

Dear Skimask,

I have clearly mentioned that I have never used a Tx/Rx module ever. I tried to explain something which is not practically tested by me. So I was seeking support to correct me if I state something.

I was trying to clarify the same thing.
In the earlier post, if you are trying to explain something and asking me if your explanation was correct, then, I would have to say, for the most part, yes. Train the receiver with a stream of 1's and 0's, keep the receiver happy with an equal number of the one's and zero's equal, and all should work well.