ColdFire/68K Microcontrollers and ProcessorsのトピックRe: I2C Initialization for MCF 5485

I2C Initialization for MCF 5485

pinakin — Wed, 30 Jan 2013 15:09:26 GMT

I am working on I2C Driver for MCF 5485. The reference manual for this coldfire version provided an initialization sequence when the driver comes up. This sequence can also be used to reset the I2C driver. The sequence is as follows:

/* section 28.5 Initialization Sequence */

I2ICR = 0x00

I2CR = 0x0

I2CR = 0xA

dummy read of I2DR

I2SR = 0x0

I2CR = 0x0

I2ICR = 0x01

The 3rd line sets I2CR to a value of 0x0A. This seems incorrect to me as the last 2 Least significant bits are reserved and should always be cleared. I refered to reference manual of an older MCF controller (5282) and it sets this register to a value of 0xA0. I suppose this is an error in the reference manual of MCF5485. Could yoou please confirm this?

Re: I2C Initialization for MCF 5485

TomE — Wed, 30 Jan 2013 23:05:15 GMT

I've checked my MCF5329 Reference Manual. It uses 0xA0 as well. Those values correspond to setting the IEN and MSTA bits, and makes a lot more sense than the obviously wrong one in the MCF5485 manual. The latest manual is Revision 5.

The current "MCF5485RMAD.pdf (Reference Manual Errata) says of the Revision 5 manual "None to report". You've found one!

Searching on Freescale for 'I2CR = 0xA" gets 40 hits, as does searching for "I2CR = 0xA0". The Search can't be made specific enough to catch this difference.

Letting Acrobat search through my own copies shows the 5301x, 5373, 54455, 52223, 52211, 5282, 5275, 52235, 52277, 5213, 5208, 5235 and 5329 manuals are OK. The 5307, 5475 and 5485 ones are wrong. The 5307 one is ancient (stamped "Motorola") and is probably where the 547x manuals were copied from.

Tom