Guys,

I'm using the 12864 LCDS4 DSDM with the Hitec C18 compiler. I'm trying to communicate with the DS3231 I2C real time clock chip without any success. I'm using the built in MSSP module rather going the bit banging route. The routine has been tried & tested on a P16F886 (which works fine) with a small change due to 1 register name change.  I have double checked my code against the Microchip AN989 application note for 18F devices.

I've spent a few hours on this to no avail. Has anyone tried using the MSSP module to communicate with I2C devices or is there a known problem that I'm not aware of?

Thanks,

MikeH. 

 What Digole display module you have: serial module or smart module?

 I'm using the smart module.

 I've got it working by bringing the clock rate down to 10Khz rather than the 100Khz rate specification!  I shall now slowly increase the clock rate until it fails again. 

 Clock rate now back at 100Khz & everything working OK - not sure where the mistake was!!

 Did you add pull up resistors when using I2C?

 Yes I did - I'm using a small ready built module complete with pull-up resistors. There must have been a mistake somewhere in my coding because it is reading & writing fine now. The display is destined for a new central heating controller - really pleased with the display, has reduced the component count & size considerably.