Date: Sat, 15 Sep 2007 02:59:27 +1000 From: Ian Smith <smithi@nimnet.asn.au> To: freebsd-questions@freebsd.org Subject: how to use iic(4) Message-ID: <46EABDEF.9080403@nimnet.asn.au>
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I don't know where else to post this, so I'm hoping someone here can
spare me a clue.
We're building a small board with two AVR Tiny MCUs chatting to each
other over an opto-isolated I2C-compatible bus, hopefully at 400kHz.
I hope to use the iicbb(4) on lpbb(4) parallel port interface to talk
with either of these MCUs for debugging, control and data acquisition.
iic(4) says:
=======
The iic character device driver provides generic i/o to any iicbus(4)
instance. In order to control I2C devices, use /dev/iic? with the fol-
lowing ioctls:
Ioctl Description
I2CSTART send start condition to the specified device (with 7-bit
address) on the bus
I2CSTOP send stop condition to the bus
I2CRSTCARD reset the bus
You may also use read/write routines, then I2C start/stop handshake is
managed by the iicbus system.
=======
Does the latter statement suggest that ordinary reads from or writes to
/dev/iic? could be performed by redirection of say echo and read from a
script? Or is the device only accessible by ioctl from eg a C program?
Also, iicbb(4) is a master-only interface. I can work with that, but if
anyone knows of any iicbus slave-mode code I'm all eyes ..
Cheers, Ian (please cc me)
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