analog to digital conversion
#1
Posted 09 March 2012 - 01:40 AM
#2
Posted 09 March 2012 - 02:20 AM
#3
Posted 09 March 2012 - 02:40 AM
Hi allen,
The low-end of the ADC for Netduino's SAM7X MCU is around 2.7V, and the analog resolution is "within a few millivots" per unit...
For this application, you'll want to use an external ADC chip designed for such small readings (and accuracy at those readings), and then drive it via SPI or I2C.
Chris
A better idea would be to add an external operational amplifier to increase the voltage to a range the N+ can accurately convert.
#4
Posted 09 March 2012 - 03:25 AM
Currently the analog port on my netduino plus only has a 1024 resolution and I need a lot more than that.
Or probably a combination of both.
- Get a 12 or 16 bit ADC that talks SPI or I2C, preferably one that somebody has already written Netduino code for.
- Work out what its analogue input requirements are
- Use some linear circuitry ( op amp) to bring the raw signal into this range, in such a way that you use the full extent of the range.
#5
Posted 09 March 2012 - 04:15 AM
#6
Posted 09 March 2012 - 04:16 AM
#7
Posted 10 March 2012 - 06:16 AM
#8
Posted 10 March 2012 - 07:54 AM
#9
Posted 01 April 2012 - 10:49 PM
#10
Posted 03 April 2012 - 12:12 AM
#11
Posted 06 April 2012 - 05:15 AM
#12
Posted 06 April 2012 - 06:43 AM
Max voltage would be 5v min would be 0. The sensors are measuring weights that can be from 0 to about 30 tons. Need to be accurate within a pound. 2000 pounds in a ton (I believe) so 30*2000 gets me to needing 60k granularity (16bit probably would work). I'm measuring 4 channels and we need to read them at least once a second.
Is it a single case, so 4 sensors at all, or do you need several system like this?
I mean, would be considerable *at least* one/two hundreds of such a sensor interface?
The problem is the cost, which can fall whereas the number of modules are high.
#13
Posted 17 April 2012 - 07:04 PM
Is it a single case, so 4 sensors at all, or do you need several system like this?
I mean, would be considerable *at least* one/two hundreds of such a sensor interface?
The problem is the cost, which can fall whereas the number of modules are high.
Only 4 sensors per unit and only 1 unit per truck. So we only have to read 4 sensors on 1 unit every 1 second for an entire system.
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