Hello, Newbie here, I can't find any info on ADC122S021 chip for Arduino. I want to use this for a pH sensor and LM35 Temperature sensor. What's correct way to wire ADC122S021 to Arduino and any available codes to start?
Have You tried Google on ADC122S021 Arduino? Plenty of suggestions....
I did, couldn't find anything. link?
Try again, look harder.
https://e2e.ti.com/support/data-converters/f/73/t/523691?adc122s021-array-with-arduino-uno#
Any help?
Why do you need an external ADC to measure ph and temperature?
I don’t see what the additional two bits of resolution get you, unless of course this is a homework assignment. There are tons of examples using the Arduino internal ADC using those sensors. Why not start there? You’ve got to learn how to walk before you can run.
A ratiometric ADC122S021 might not be the right A/D for a pH sensor with absolute (voltage) output.
An ADS1015 or ADS1115 breakout board might be better suited for your (unspecified) pH sensor.
Drop the difficult to use LM35, and get a digital DS18B20 temp sensor.
Leo..
Arduino internal ADC is 1.1v reference, Don't I need at least 3.5V.
WattsThat:
Why do you need an external ADC to measure ph and temperature?I don’t see what the additional two bits of resolution get you, unless of course this is a homework assignment. There are tons of examples using the Arduino internal ADC using those sensors. Why not start there? You’ve got to learn how to walk before you can run.
Savefilez:
Arduino internal ADC is 1.1v reference, Don't I need at least 3.5V.
For what...
An LM35 is best measured with 1.1volt Aref.
But "a pH sensor", no idea until you post a link.
Leo..
I plan on using lmp7721 with ATMEGA32U4.
The LMP7721 is an opamp, and a pH sensor outputs AFAIK a voltage.
So you're planning to design a pH sensor with this opamp?
If so, post a diagram.
I think you need an A/D with internal voltage reference (the ADC122S021 doesn't have one).
A 16-bit ADS1115 (with internal reference) seems a much better choice.
Leo..
I removed the ADC and added ADS, https://easyeda.com/haroldalv/NewPH , not pretty, did this real quick.
Wawa:
The LMP7721 is an opamp, and a pH sensor outputs AFAIK a voltage.
So you're planning to design a pH sensor with this opamp?
If so, post a diagram.I think you need an A/D with internal voltage reference (the ADC122S021 doesn't have one).
A 16-bit ADS1115 (with internal reference) seems a much better choice.
Leo..
Hello Wawa,
Can you tell me if i'm using ADS1115 correctly with lmp7721, Thanks.
Using resistors in series with the SDA and SCL lines indicates lack of experience.
There could be many more 'mistakes'.
Shouldn't you design something easier first.
Leo..
I must of been looking at the wrong datasheet :o , But clearly shows the correct way on the datasheet and on Adafruit. Sucks being a noob but I will keep reading. Thanks.
SDA/SCL pins directly connect to other SDA/SCL pins.
Pull up resistors go from those lines to VCC (5volt?) of the chips.
Only one set of pull up resistors is needed.
Values depends on the capacitance of the bus.
10k should do on a small circuit board.
Leo..
Wawa:
SDA/SCL pins directly connect to other SDA/SCL pins.
Pull up resistors go from those lines to VCC (5volt?) of the chips.
Only one set of pull up resistors is needed.
Values depends on the capacitance of the bus.
10k should do on a small circuit board.
Leo..
Hello Wawa, can you check again and let me know if I did it right this time. I also added ferrite beads like adafruit board. Thanks.
I2C lines seem correct now.
Not sure if if it's wise to get a reference voltage for the active shield from a potentially dirty/unstable 5volt supply.
I would have used a proper voltage reference there.
Leo..