16F88 RS232 don't receive data.

[beth]

Hello everybody here, how are you? ;) I am looking for some "inspired" sould that can help me with this dissapointing problem :P.

I am not a begginer in the microcontrollers world, and this is getting me scary in some way, because the troubleshotting code is so easy and well, I will describe the problem.

I am working in a project that used a 16f628, and I decided to start with the new and more powerfull replacement in his category, the 16f88, and baby, after the switch I lose the rs232 communications.

I am using a max232 and is working ok, because I switch tx & rx to a 16f876 that is in the same protoboard, and works ok, (the circuit uses a 16f876 and a 16f88).

I can send data from the 16f88, but not receive that, but is so strange, the rx pin goes low all the time (in the 16f876 is high) and if I see the signal using a scope I see a 0v signal most of the time, except when I am sending data from the pc, in which case I see small variatons (the square wave) of 200 millivolts only. If I do the same test procedure in the 16f876 I see 5v most of the time in the rx line and goes to 0v when I am sending data from the pc.

I think that it must be a problem of the fuses, of the configuration, of my code or the compiler, I hope that the compiler does his work ok, but nowadays I did not trust in my shadow ;). This is my first attempt with a 16f88 and I don't know if I am configuring ok the system clock, the different options of the code, and maybe I am making a mistake, really I dont know what I am doing bad.

Here you have the code, its so simple because I started a new project for testing the communications, so please if someone can take a quick look and ... ;) :

(Thanks in advance, best wishes, and sorry for my bad english ;) )
(Compiler version 3.227)

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[Module.h]
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[Ttelmah]

Try adding:
#bit B2TRIS=0x86.2
in the definitions,

Then after the initialisation, but before your first printf, add:

B2TRIS=1;

Unfortunately, some compiler versions, set the TRIS incorrectly for the receive pin, leaving it defined as an output, which then stops the data being received.

Best Wishes

[beth]

Ttelmah, thanks for your help, it works at the first try. There is a beer waiting for you here at Spain ;).

Again a lot of thanks. Best regards ;).

[Ttelmah]

Thanks.
Glad it worked. :-)

Best Wishes

[guest]

I have a similar problem. I can transmit data from the pic to the pc correctly. but when I try the reverse I can never get the pic to pause for my input.

I have verified the hardware using another compiler. (oshonsoft pic simulator)

[PCM programmer]

Make a test program similar to the one shown in this thread.
See if it works.
http://www.ccsinfo.com/forum/viewtopic.php?t=25130