@DigitalBob im powering everything from 5v which is being boosted from 3.7v (portable phone charger) on the second 3208 could i tap directly to the 3.7v source and monitor battery voltage?
That you could, the operating voltage for the 3208 is 2.7-5.5 VDC. I like to run mine with 5V and and a Ref02 reference, this way the 4095 bits match up for 5V in.
One extra channel to monitor battery voltage could be provided with a couple of resistors and capacitors. With RCTIME, you'd use one Prop pin to measure the time required to charge a capacitor. With Sigma-Delta, you'd measure io time on one Prop pin required to keep a capacitor charged to the Prop input threshold on a second pin. Either one of those is a function of the battery voltage as input.
The ADC I used on my BASIC Stamp data loggers was the TLC2543. It has 11 input channels, 12 bits, and has a simple SPI interface very similar to your 3802. These days, it is not so popular, being for a 5V supply and lacking the bells and whistles of the more modern converters like the AD7490 or MAX11616. (Bells and whistles might trip you up for code development.!) I do have a few TLC2543 chips in DIP20 or SSOP20 lying around that I'm not using, and I'd be happy send you a couple of them for the price of a stamp (postage that is ). Here is the code to read a channel on the TLC2543 on a BASIC Stamp. The method would easily transfer to the Prop.
' --- TLC2543 Analog to digital converter -----------
ADread: '
LOW ADcs
SHIFTOUT ADsdi,ADsck,MSBFIRST,[ADch<<8\12] ' select channel and convert
SHIFTIN ADsdo,ADsck,MSBPRE,[result\12] ' conversion finishes already
HIGH ADcs
RETURN
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The ADC I used on my BASIC Stamp data loggers was the TLC2543. It has 11 input channels, 12 bits, and has a simple SPI interface very similar to your 3802. These days, it is not so popular, being for a 5V supply and lacking the bells and whistles of the more modern converters like the AD7490 or MAX11616. (Bells and whistles might trip you up for code development.!) I do have a few TLC2543 chips in DIP20 or SSOP20 lying around that I'm not using, and I'd be happy send you a couple of them for the price of a stamp (postage that is
' --- TLC2543 Analog to digital converter ----------- ADread: ' LOW ADcs SHIFTOUT ADsdi,ADsck,MSBFIRST,[ADch<<8\12] ' select channel and convert SHIFTIN ADsdo,ADsck,MSBPRE,[result\12] ' conversion finishes already HIGH ADcs RETURN