Hi Dave,

My application will need me to get an ADC with 3 or more analog inputs with a 16-bit resolution. I would prefer to use a I2C interface since I managed to make the built-in 10-bit ADC (on the robostix) to work and start collecting data.

I was looking at the range of ADCs available from Maxim and I'm now trying to choose between one of the following (please advise me if I'm looking at the correct ADC to suit the robostix):

1. MAX1167 (http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3997) - 4 channels and 16 bits but using SPI interface.

I've looked at the gumstix wiki (http://docwiki.gumstix.org/Robostix_SPI) and realised (please correct me if I'm wrong) that the four pins needed to interface with the ADCs from the microcontroller will be difficult to solder on. Is there another way that I can connect the four wires on? Also how different is programming the ADC using SPI (over I2C)?

2. MAX1169 (http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3659) - 1 channel and 16 bits and using I2C interface.

Can I use 3 x MAX 1169 ADCs to increase the resolution? If this is OK, how can I then build that onto the robostix? And can I apply the same way (as the robostix ADC) to "get" the values from the new ADCs?

Ideally I would prefer to avoid using the robostix and the reason I'm having it on board now is because of the built-in 10-bit ADC. Please kindly advise me on the possible solutions to incorporate the Maxim ADC? I've also looked at the TI ADC (ADS 7825 - 4 channels 16 bits and using I2C interface but I'll be less inclined to use this one if I've a choice).

Thanks for all your help.

Peck Hui

At 09:46 10/10/2007 -0700, you wrote:
Hi Peck Hui,

> Can I ask if anyone tried to incorporate a 16-bit ADC to work with the gumstix? I've got a robostix which can provide up to 10-bit ADC and the resolution does not seem to be enough for my application.
> I'll greatly appreciate if anyone can advise me on the method they used - to use an external ADC on a separate board (?and stick it on the existing robostix) or to modify the existing robostix?

You can get I2C or SPI based A/D converters. Which one to get depends
on exactly how/where you want to connect it. Maxim carries a bunch and
you can get free samples (most of the time).


> Also does anyone has a schematic of the gumstix/robostix bus configuration? I'll like to know the layout of the 60-pin (not the I/O pins on the board) so that I can do the necessary modification if there is a need to.

All of the schematics for the daughtercards are in Eagle format and
can be found over here:

You can download a free copy of Eagle from <http://cadsoftusa.com/>

Dave Hylands
Vancouver, BC, Canada

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