Why am I getting these (mostly) good readings with the built in ADC of the Arduino Uno (10 bits resolution):
and these scattered values (same analog sensor used) with the external LTC1418 ADC (14 bits resolution of which the last 2 bits were dropped) ?
For what is worth, the sensor is an G-NSDOG1-006 Also I once had this anomalous outcome from the built in ADC:
I am using the external ADC as shown in "Figure 24. Internal Conversion Clock Selected. Data Transferred After Conversion Using an External SCLK." at page 25 of the spreadsheet above. All of the readings were taken at every 0.5 seconds.
The electrical schematic is what they recommend in the same document:
The LTC1418 chip is soldered to a SSOP-to-DIP adapter PCB which is inserted into a solderless breadboard.
My final goal is to stabilize the external ADC unit (the LTC1418 chip)'s output.
In response to @Brian Drummond
- For the supposedly stable 3v3 output from the arduino and USB power the jitter stays within 11 units.
- For the supposedly stable 3v3 output from the arduino and battery power the jitter stays within 6 units.
- For the GND and USB power the jitter stays within 5 units.
- For the GND and battery power the jitter stays within 5 units.