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Date:      Wed, 26 Mar 2008 03:08:47 +1100 (EST)
From:      Ian Smith <smithi@nimnet.asn.au>
To:        Bruce M Simpson <bms@incunabulum.net>
Cc:        nsouch@freebsd.org, FreeBSD stable <freebsd-stable@freebsd.org>
Subject:   Re: lpbb broken in 6.x?
Message-ID:  <Pine.BSF.3.96.1080326013404.3409B-100000@gaia.nimnet.asn.au>
In-Reply-To: <47E8F3A4.50807@incunabulum.net>

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On Tue, 25 Mar 2008, Bruce M Simpson wrote:
 > Ian Smith wrote:
 > > To finish off completely hijacking your thread :) does anyone know of
 > > anything that can run a master/slave interface like pcf(4) which appears
 > > to have been an ISA bus only device?  I don't have C skills to write
 > > one, though 400kHz master and slave routines in AVR asm were fun :)
[..]

 > Thanks for the hints. I don't have smbus in the kernel, nor do I have 
 > any other i2c device drivers loaded in the system.

Excuse wild guesswork.  What form would loader.conf hints take for lpbb?

 > I stopped using smbus when it became pretty clear that it wasn't doing 
 > anything useful for me (it could never see CPU fan readouts or anything 
 > like that when I tried it on 3 different PIII era systems).
 > 
 > I agree a pcf(4) style interface would go some way towards solving the 
 > problem, however, solder plus 74LS05 costs next to nothing, plus the 
 > "leet value" of having a circuit schematic in the man page had to be 
 > tried out. I think we're losing out there if it's not working, though.

Maybe nobody else has used lpbb recently, or this would have come up?

Agreed the interface is cool, and about my hardware level, but I've had
no motivation to build one until I found a useful driver for the task.
Seems ideal for what you're doing though, with bus speed not a factor.

I see that even pcf with interrupt driven bytewise send/receive was only
good for /* select bus speed : 18=90kb, 19=45kb, 1A=11kb, 1B=1.5kb */ ie
a fastest SCL of 90kHz by the PCF8584 spec, about 10kbytes/s flat out. 
I'd be easier, and faster, to talk 115.2kbps via sio|uart with the AVR.

Just googled up an NPX PCA9665 capable of up to 1MHz I2Cbus, so Philips
at least have moved along.  Maybe someone will do a USB<->I2C dongle?

 > PS OpenBSD look like they took NetBSD's i2c and ran with it...

Will check, thanks.

cheers, Ian




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