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DarrenY
09-05-2007, 04:44 PM
Hello,

Can someone recommend a high resolution, easy to use ADC for use with the Propeller?

It's to be used to collect accelerometer and gyro inputs so will need at least 5, preferably 6 channels.

Preferably I2C, but SPI recomendations would be good as well.

Thanks,
Darren.

Leon
09-05-2007, 04:55 PM
How many bits?

Leon

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DarrenY
09-05-2007, 05:03 PM
At least 12, pref 17 bits

Jonathan
09-05-2007, 10:20 PM
SMT or thru hole? I only found i2c stuff with more than 2 channels in SMT. If you find a 12 bit ADC with 4+ channels, i2c and thru hole, lemme know.

For now, I am still using a TLC2543, 10 channels, 12 bits, good chip, easy to use, SPI interface, thru-hole.

17 bit ADC's require careful circuit layout to use very effectivly. Those last 5 bits can be a pain.

Jonathan

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Javalin
09-05-2007, 10:28 PM
Jonathan,

Look at the microchip range - MCP3201/2/4/8 (channels). They are SPI and easy to drive using Spin or ASM. The MCP2308 is 12 bits.

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010534

J

DarrenY
09-06-2007, 01:31 AM
OK, I've found a 12-bit, 4/12-Channel I2C.....

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3271

And a single channel 18-bit I2C....

http://ww1.microchip.com/downloads/en/DeviceDoc/22003b.pdf

Tracy Allen
09-06-2007, 02:05 AM
More questions... How fast? The mentiion of accelerometer and gyro suggests a need for speed and even practically simultaneous measurements on all 5 or 6 channels. Within any ADC architecture, more bits means slower speed. ADCs with built-in multiplexers usually can convert on only one of the channels at a time. I2C ADCs tend to be relatively slow, due to command overhead. Even so, in high speed mode some single channel I2C 12 bit devices can reach over 100 ksps. E.g. ADS1000 from TI/Burr-Brown.

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Tracy Allen
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DarrenY
09-06-2007, 02:51 AM
Jonathan:
Pref DIP for proto work and then SMT later on.

Tracy:
I don't know! - it's the first time integrating sensors for me.

Looking at it a bit more, i'm pretty sure 12-bits is the way to go.

Looking through the forum posts, i'm not the first to integrate these type of sensors - what have other people used?

Basil
09-06-2007, 03:56 AM
Hi Darren,

I am using a MCP3208 (or MCP3204/2).

12 bits 8 channel (or 4 or 2) and comes in through hole and SMD.

Im not using the standard library, so not sure what the max sample rate for that one is, but with a custom library can get 2500 x 10 sample averages per second.

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DarrenY
09-06-2007, 06:26 PM
Thanks, I went for the MCP3204 - good call.