I2C Hardware with PIC 16F877 and PCW Ver 3.184 ????

[Jean - Pierre]

Hello All,


It is possible that the PCWH compiler ver 3.184 have some trouble with the I2C hardwares functions because when I use the software functions, all is ok but when I switch to the hardware functions, my PIC 16F877 stop
to the "i2c_start()" function.

I have read the other topics but my code seems to me good...

Did somebody it already use I2C hardware with a PIC16877 and PCWH
3.184???

Can you help ?

Thanks !

Jean - Pierre

[Ttelmah]

I used most versions of CCS in the past, and cannot remember having a problem around this time wth I2C. However note the comment on version 3.223, about a problem with I2C_START on some chips.
Also, I am assuming that since you were previously doing this in software, the unit is running as a 'master', and that the unit at the other end, is a I2C peripheral, and not another PIC. Otherwise there is a silicon errata that may apply.
There are some things possibly worth checking:
Which 'speed' are you selecting?. Even if you are selecting the slow rate, the actual transfer speed may well be faster with the hardware, than with the emulation. I have seen some issues in the past with the I2C baud rate being incorrectly set. Use a software simulator, and verify that the BRG has a value that makes sense for your clock rate. Which inputs were you using for the software interface?. The hardware interface, has Schmitt trigger inputs, and requires the signals to get to higher levels than an input with a TTL buffer. Are your pull-up resistors low enough to guarantee this?.

Best Wishes