Hardware I2C

[Darrel Taylor]

I2C is Synchronous in nature. So things only happen when the clock is toggled.
If the I2C routines get interrupted, it won't matter, because the clock won't toggle either.

SERIN/OUT requires certain timing between the bits, and fails when interrupted because that timing changes.
I2C won't care.
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[Kamikaze47]

Oh cool. Good to hear.

Thanks DT and skimask for ur help.

[Kamikaze47]

My PBP manual says:

"The timing of the I2C instructions is set so that standard speed devices
(100kHz) will be accessible at clock speeds up to 8MHz. Fast mode
devices (400kHz) may be used up to 20MHz. If it is desired to access a
standard speed device at above 8MHz, the following DEFINE should be
added to the program: DEFINE I2C_SLOW 1"

My 48Mhz OSC is obviously not "up to 20Mhz".
Do you think it still run at 400kHz by default with a 48Mhz OSC?

[skimask]

Do you think it still run at 400kHz by default with a 48Mhz OSC?

If they don't, set I2C_SLOW and see what happens.
I don't have access to the macro's here with me, but checking the I2C macros might show whether or not the timing is compensated for with the various oscillator DEFINE's.

[Kamikaze47]

I cant make much sense of the macros, but i'll just see what happens.

Still waiting for the EEPROM chip to be delivered, but figured I can make a start on my code anyway.

[skimask]

Still waiting for the EEPROM chip to be delivered, but figured I can make a start on my code anyway.

I know I've been able to get a regular ol' 24LC256 working without a problem at 40Mhz.

Before you start writing code (and failing! ), be sure to do a search here for the '512 types. There's a couple of small issues that seem to trip people up a lot.

[Kamikaze47]

I've been reading the posts about it, and getting a pretty good idea of where to look if it doesn't work first time. I've written a test program just to write 32 bytes to the EEPROM and then read it back and check against the original data. Now just gotta wait for the chip to arrive.

One thing I did notice is that people are saying you have to wait 10mS between writing and reading. Does this also apply to just reading? i.e. If I read 32 bytes with [STR string\32] and then do the same thing again to read the next 32 bytes, will I have to wait 10mS between? I'm sure this info must be in the data sheet, but i looked thru the data but couldnt work it out.