Serial data sending#do someone came across programming 16f676 with TRH031M?

[Hanson]

Dear experts,

Currently I am trying to program pic16f676 as a microcontroller to send serial data from TRH031M (kinda 13.56MHz transmitter)
http://www.farnell.com/datasheets/460824.pdf

Im using SPI serial interface in TRH031M and I faced difficulties in figuring out my coding. Kindly help.

[Charlie]

The answer is obvious. There's an error in your code.

[Hanson]

Dear Charlie,

I am new in picbasicpro. Where can i find a sample SPI coding to be referred? Currently Im using TRH031M as "slave" in SPI mode and pic16f877 as a MCU (master in SPI mode)

[HenrikOlsson]

Hi,
Start by taking a look in the PBP3 installation folder. There's sub-folder called EXAMPLES\GENERAL PBP.
The file shift.pbp demonstrates how to use the SHIFTIN/SHIFTOUT commands and the files spimast.pbp and spislave.pbp demonstrates how to use the SSP/MSSP module in the PIC to do SPI at the hardware level.

The PBP manual covers the use of SHIFTIN/SHIFTOUT and there should be plenty of example code around the forum. Probably not exactly the code you need but plenty to get ideas from. If you get stuck post specific questions and you'll most likely get plenty of help.

With that said, if you're new to PBP then perhaps getting up to speed by interfacing a simple shiftregister or something as a start might be a good idea.

/Henrik.

[Hanson]

Hi Henrik,

As per my understanding, to perform SPI between a master and a slave, 2 programmable PICs are needed (1 for master& 1 for slave) while TRH031M I am using is kinda transmitter which cannot be programmed. So, can I send only data from my PIC16f877(master) to TRH031M without programming TRH031M? Kindly advice!

Thanks.

[HenrikOlsson]

Hi,
With SPI there's always one master and one or more slaves. The master is always responsible for generating the clock. In your case the PIC would be the master and the TRH031M would be the slave. Master/slave has nothing to do with the direction of the data, it can go from master to slave, from slave to master or both ways.

So, yes, of course you can send and receive data to/from the TRH031M without reprogramming it - it's already "programmed" to act as a slave.

/Henrik.

[Hanson]

Hi Henrik,

Thanks alot! My brain isn't functioning well just now. Sorry for the confusion.

[Hanson]

Hi Henrik,

Now considering I have successfully received and stored the data in PIC16f877 as "ActualData" and I wish to send the stored data to the "slave (TRH031M)".
Can I use SHIFTIN/OUT method to shift data into SDO pin and send to trh031m? Following is my coding:

************************************************** ********************************************
'send received data from MU to TRH031M (master to slave)
ActualData var word[8]
j var byte[8]
B0 var byte

send1:
SHIFTIN SDI, SCK, MSBPRE, [ActualData\8]
j=ActualData
SHIFTOUT SDO, SCK, MSBFIRST, [j]

SSPBUF = "?" ' send ? to start conversion
GoSub letclear ' wait for buffer to clear
IF SSPBUF<>"!" Then send1 ' wait for reply (!)

For j = 0 to 7 ' loop for 8 characters
SSPBUF = 0 ' write to SSPBUF to start clock
GoSub letclear ' wait for receipt
B0[j] = SSPBUF ' store received character in array
Next j ' get next character
Return

letclear:
IF SSPIF = 0 Then letclear ' wait for SPI interupt flag
PauseUs 25 ' 25uS fudge factor
SSPIF = 0 ' reset flag
Return

************************************************** ************************************

Regards/

[HenrikOlsson]

Hi,
I don't know if it's you or me who are the most confused right now.....
You seem to be mixing SHIFTIN/SHIFTOUT with the use of the MSSP module, use either or. And, previously you said you used SEROUT on another PIC to send data, then you can't use SHFTIN to receive it - if that's what you're trying to do. And, no, you can't use any of the methods to shift data into the SDO pin since that is the data output pin.

ActualData var word[8]
j var byte[8]
B0 var byte

Any reason for ActualData to be WORDS?

send1:
SHIFTIN SDI, SCK, MSBPRE, [ActualData\8]
j=ActualData
SHIFTOUT SDO, SCK, MSBFIRST, [j]

Not sure what the purpose of this is but there's no reason to assign the value of ActualData to J and then send J out using SHIFTOUT, you could just as well shift out ActualData directly (instead of a copy of it).

For j = 0 to 7 ' loop for 8 characters
SSPBUF = 0 ' write to SSPBUF to start clock
GoSub letclear ' wait for receipt
B0[j] = SSPBUF ' store received character in array
Next j ' get next character
Return

Here you're treating B0 as an array when it's decalred as a BYTE. This is a critical error as it will write to memory location "beyond" B0 and corrupt what ever is there. PBP does not do any boundry checks on arrays so you need to be careful.

This post probably isn't of much help to you but I've quite honestly lost track of what exactly you're trying to do. Now, we've got SERIN, SHIFTIN/SHIFTOUT and the use of the MSSP module in the mix - all at once and I'm struggeling to keep up. Again, I suggest that you get used to various ways of doing SPI by interfacing something simpler than the TRH031M - which, by the way, I've never used so I don't know how it works. But I looked, briefly, at the datasheet and nowhere can I find that you're supposed to send "?" to start a "conversion" - I thought the chip was for RFID communications, not a converter....

/Henrik.

[Hanson]

Hi,

Sorry Henrik for making you confused. I am not sure that I can use SERIN with SHIFTIN/OUT so I mistakenly mixed them up.

Actually what Im doing is transmit a data at 13.56MHz by using TRH031M and the data is from pic16f877. Since trh031m has 4 type of modes, SPI,parallel etc, i configured my hardware to perform SPI mode. So Im trying to use "master slave" communication to send my data from PIC to trh031m as trh031m already pre-configured as a "slave" by default which u told me in the previous comment.

Can you kindly teach me what is the correct way to send my received data from PIC to trh031m? Do "master slave" communication work in performing my task?

appreciate your kind helps.

Regard.

[HenrikOlsson]

Hi,
All I can say is that the PIC and PBP supports SPI communcation, either by using SHIFTIN/SHIFTOUT or using the MSSP peripheral module built into most devices. That gives you the interface between the PIC (master in this case) and the TRH031M (slave in this case). I see no reason for it not to work, however there are occasions where SHIFTIN/SHIFTOUT is NOT an option because the the slave devices is shifitng in and out data at the same time, in those cases you must use the MSSP module because the SHIFTIN/SHIFTOUT either shift data in OR shifts data out they can't do both simultanously.

But, the TRH031M is a complicated device, it's not as simple as just "send some data" to it. It needs setting up, it needs commands sent to it, it needs data sent to it, it needs new commands sent to it, it needs to be polled for status and so on. You absolutely must read and understand the datasheet or you won't be able to make this work. Again, I've never used the device so *I* don't know how it works, I've just very briefly browsed thru the datasheet.

I strongly suggest you put your PIC, a 74*595 (serial in, parallel out) and a 74*165 (parallel in, serial out) shiftregisters, a couple of LEDs and a couple of switches on a breadboard and get used to communicating with those. Use SHIFTOUT to write data to the 74*595 and SHIFTIN to read data from the 74*165. When you have that working and understand how it works, try the MSSP module instead of SHIFTIN/SHIFTOUT. With that you'll be able to write one byte to the 74*595 and read one byte from the 74*165 all in one go - which MIGHT be what's needed for the TRH031M - I'm not sure.

THEN get back to the TRH031M.

/Henrik.