I2C Read/Write problems

[skimask]

Can anyone give me an idea as to why the clock is so far off? The book says 400KHz devices are accessible if the clock is above 8MHz (I'm using 20), but my clock is at 122Khz. The manufacturer of the board said this wasn't a problem so long as the PIC supported 'clock stretching'.

See Post #2...
400Khz is the MAXIMUM for most fast I2C devices. It's not neccessarily the speed that the PIC is communicating to said I2C device. I2CRead/I2CWrite are software, 'bit-banged' commands, not hardware.
If you ran your PIC clock at 40Mhz vs. 20Mhz, the I2C clock may very well jump up to 244Khz.

[Acetronics2]

See Post #2...
400Khz is the MAXIMUM for most fast I2C devices. It's not neccessarily the speed that the PIC is communicating to said I2C device. I2CRead/I2CWrite are software, 'bit-banged' commands, not hardware.
If you ran your PIC clock at 40Mhz vs. 20Mhz, the I2C clock may very well jump up to 244Khz.

Hi, Ski

You forget the 24 FC series ... @ 1Mhz !!!

Alain

[skimask]

Hi, Ski
You forget the 24 FC series ... @ 1Mhz !!!
Alain

Don't they call those 'HIGH' speed, a bit like USB? Slow, Fast, High?