Re: [avr-gcc-list] Learning about using SPI

[Joerg Wunsch]

Juergen Harms <address@hidden> wrote:

> ... and saw that some AVR processor have hardware support for I2C,
> some for SPI - next thing I will have to do is deciding which
> hardware to start with, hence my question.

I think all AVRs (except a few really old ones) do have hardware SPI.
This interface is also used as the ISP interface (in-system
programming), because ISP is basically not much more but an SPI slave
that is initiated by a particular wake-up sequence while keeping
/RESET low.

Many of the recent ATmega devices offer hardware I²C (called TWI,
supposedly for legal reasons).  I think the major exception is the LCD
controller family (ATmegaXX9/ATmegaXX90) and their LCD-less
counterparts (ATmegaXX5/ATmegaXX50).  All recent AVRs that don't offer
hardware I²C (that includes all the recent ATtinys as well) do offer a
so-called USI module instead (universal serial interface) which could
be used to emulate an I²C, but it takes a bit more of firmware to
implement the protocol (though there are appnotes available).

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)