I2C master mode takes a lot of real estate in silicon, however it
is trivial in software.  Take a look at the I2C portion of a 17C756
die (it has master mode), it's a bit bigger than I2C chunk of a 16C74.

>From what I've heard from Microchip, the low and mid-range parts
didn't have I2C master for cost savings.

-Keith Wheeler
ARMA Design                             http://www.ARMAnet.com/


At 08:31 AM 12/31/98 -0700, Matt Bonner wrote:
>Clyde Smith-Stubbs wrote:
>>
>> But the good news is that master mode is not too hard to do in software
- slave
>> mode is considerably harder, which is perhaps why it has hardware support.
>>
>I believe it's because Philips' I2C patents - they demand a royalty for
>hardware implementations of master mode, but not slave.  Didn't MChip
>announce plans for a PIC with master mode hardware?  (I can't find my
>copy of their latest product line card - maybe they already have one.)
>
>--Matt
>
>