PIC16F88 receive interrupts apparently not properly initiali

[Gerhard]

I have recently received some 16F88s with the intention to port an existing working sensor application from a PIC16F876 to the 16F88 hoping only minor IO changes would be required. The same program runs successfully on a 16F876/877, and PIC18F452 without any major changes other then chip specific mods.

My application utilizes a command interpreter which uses interrupt driven capture of incoming characters via a RS485 link at 9600 Baud.

It turned out, the receive interrupt would no longer function. The RCSTA register would always initialize to zero, although on the other PICS it would be initialized to 0x90. While the RCSTA register was left in this state, RS485 transmissions would work fine. However it was not possible to receive any characters until I manually set RCSTA to 0x90. At this point interrupts were detectable, however sending characters was no longer possible. Since I was using RS485 mode, I could detect the TX active pin, but never any data being sent back.

Anyways, I would be curious if somebody also encountered a similar problem. It may be too early to blame the compiler. Perhaps, I failed to initialize the chip in some special way, although the other chips mentioned run just fine with the serial communications setup used.

EEPROM read and write functions worked fine.
The timer2 interupt used for application timing purpose worked also as expected.

Recompiling the same program with only the IO changes required by the other chips, would again result in a perfectly well functioning program.

I would appreciate any comments.
Thank you.
Gerhard

[Neutone]

You know how long it takes to write a byte to EEPROM is ~5mS so if you are attempting to write a byte while sending a packet or recieving a packet you will have errors.

[Guest]

[Bruno]

I use a 16F87 and have the same problem. int_rda is not working, "normal SW" serial IO on the same pins works fine. I think there are some settings in the 16F87/88 Device Table wrong.

Cheers
Bruno

[PCM programmer]

What is your version of the compiler ?

See the following post. This person had a problem with the
16F87. In their version of the compiler, the hardware USART
was not enabled. They emailed CCS and got a new version.
(Also, sometimes CCS will just email the person a new
version of the DEVICES.DAT file, and also the PCM.DLL file).
http://www.ccsinfo.com/forum/viewtopic.php?t=17431

If CCS doesn't ever respond, it's still possible to make
a "work-around" for the problem. You can do it this way:
1. Don't use a #use RS232 statement.
2. At the start of the program, put in some lines of C code
to initialize the hardware USART. Study the data sheet
for information on how to do this. Also, compile some
sample code for the 16F877, with a hardware USART,
and study the .LST file to see how CCS initializes it.
(ie., compile code for a different PIC, for which you
know the hardware USART code is actually generated).
Then just write some C code to do the same thing.
3. Create your own versions of putc() and getc(), by
following the same method described above.
4. Then use the special CCS extension mode of printf,
to re-direct printf output to your version of putc().
Example:
printf(my_putc, "Hello World \n\r");

This would require more work to implement, but if CCS does
not respond to your request to fix the Device.dat file, then
at least you have a way to finish your project.

[Jim Hearne]

Not a great deal of help but i'm using INT_RDA on a 16F88 with no problems.
Using it with completly int driven 232 TX and RX at 9600 baud.

PCW ver 3.180

Jim