Re: MAX1236 with smbus (CS5536 ACB0)

[Andreas Seidler <tetzlav-bXdiauyh1GQ7K2kJdssfr+TW4wlIGRCZ@public.gmane.org>]

Jean Delvare schrieb:
> On Wed, 15 Oct 2008 03:01:56 +0200, Andreas Seidler wrote:
>> I can access this ADC wired to a i2c-ibm_iic (build-in IBM PPC_P405)
> 
> That's not the question. Maybe the chip was wired properly on that
> system and not on the CS5563 system.
> 
> You can also try i2cdetect -r and see if it makes a difference.

I'm afraid not.


>>> If it is wired properly, then another possibility is that the MAX1236
>>> is doing clock stretching beyond what the CS5536 supports...
>> and this is my second problem: i cant read the A/D-converted values from
>> userspace (eg. with i2cget) without spezial code or kernel module?
> 
> I'm not sure if i2cget can work with this device. The transactions used
> by the MAX1236 are raw reads and writes which aren't too
> SMBus-friendly, but it you don't care too much about performance,
> i2cget may still work depending on how you read the datasheet. I
> suggest that you give it a try on the IBM PPC system where you know the
> chip is properly wired.
> 
> i2cget 0 0x34 0x81 w
> 
> should give you the raw value of the 1st ADC channel. You'll have to
> byte-swap it because SMBus specifies that words go on the wire LSB
> first.

good to know about the byte-swap with smbus!


btw:I played around with this ADC on my i2c-ibm_iic:

root@OpenWrt:/# i2cget -y 0 0x34 0x21 w

i get this values of channel 0:

OV:	0x00f0 (11110000)
1,6V:	0xaef5 (1010111011110101)
3,2V:	0x5efb (101110111111011)

but how to get the converted 12 bit value?



Regards
Andreas


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