I2C: slaves to alien master

[dhouston]

I need to use 4-5 8-pin PICs to operate as slaves to an Atmel AVR acting as I2C master. These must share the bus with an I2C FRAM (100kHz, 400kHz, 1MHz) and an I2C RTC (ST M41T81S 400kHz only).

Can the PICs (12F683 or 12F615 probably) handle a 400kHz clock?

[Darrel Taylor]

400khz would be 2.5uS per bit.
I don't think you'll have much luck writing a software based I2C slave routine that's fast enough.

You might consider the 12F1822.
It's an 8 pin device with an MSSP module.

With a 32Mhz internal oscillator, it should be a piece of cake.

[dhouston]

Thanks, Darrel.

I had downloaded the 12F1822 datasheet a few weeks back but didn't think to look at it when this came up. Now I suppose I'll have to even read it.

[mister_e]

Yeah no kidding, you need to read it, and understand it...

Says Yoda... Life's so cruel

[Charles Linquis]

You will have to use a chip with a hardware I2C port.