Re: TS-7200 Cirrus A/D converter calibration

[Jesse Off <joff%embeddedARM.com@localhost>]

Ken Hornstein wrote:
> So, according to the TS-7200 manual, the built-in EP93xx A/D converters
> have been calibrated at the factory and calibration values have been
> written to the EEPROM.  Okay, fine.  But the question I have is ...
> where is this EEPROM?
>
> I downloaded the sample code provided by TS, and that code mentions the
> TS-7250.  From looking at that code and pouring over the EP9301 manual,
> I am guessing that on the TS-7250 the EEPROM is a serial EEPROM and it's
> available on the SPI bus.  A look at the TS-7250 schematic confirms this.
> But ... I cannot find a comparable EEPROM on the TS-7200 schematic.  This
> leads me to three possible conclusions:
>
> - There are no calibration values and the documentation is wrong.
> - There are calibration values and they're in the same place as on the
>   TS-7250, I just missed them.
> - There are calibration values, but they are hidden somewhere else.
>
> Anyone have any idea what the correct answer is?
>
> --Ken
>
>   

We only started calibrating on the TS7250 and newer products.  IIRC, 
theres only a couple of the ep93xx ADC channels brought out on the 
TS-7200 because at the time the TS-7200 was released (2004) the current 
silicon of the EP9302 CPU had some errata dealing with internal ADCs.  
On the TS-7200 we did create an option for connecting a Maxim 197 ADC 
chip, but you're right there is no EEPROM on the TS-7200 to store 
calibration values so we didn't there.  It was the internal ADC's that 
needed the calibration though, the MAX197 on the TS-7200 is actually 
pretty good by itself.

//Jesse Off