0

Flicker Detection using ams AS7341
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Flicker Detection using ams AS7341

by ashish_ash on Fri Sep 24, 2021 4:51 am

Hello, I am a Newbie . The new Adafruit ams AS7341 Multispectral sensor piqued my interest because of its Multispectral sensing ability. I recently bought this sensor and I am trying to understand few concepts like Spectroscopy and Light Flicker Detection . I am making use of Raspberry Pi Zero W. So , I am using Adafruit Circuit python library.
It says that the sensor can detect ambient light flicker at 50/60Hz and return flicker frequency values of 1000Hz and 1200Hz . I tried to run the code from the Flicker detection example provided in Adafruit_Circuitpython_AS7341 repo: https://github.com/adafruit/Adafruit_Ci ... tection.py
The sensor is not detecting any frequency .
1. What could be the reason? Should I bring an incandescent or fluorescent light source near to the sensor array?
2. What exactly does the frequency value detected tell me about?
3. Any useful sources to understand more about Light flickering and it's applications?
Thanks

ashish_ash
 
Posts: 2
Joined: Mon Jun 07, 2021 1:02 pm

Re: Flicker Detection using ams AS7341

by adafruit_support_bill on Fri Sep 24, 2021 7:08 am

Incandescent lights generally do not exhibit visible flicker. LEDs, Fluorescents, High Intensity Discharge lamps such as Mercury or Sodium Vapor lamps all have a flicker. Most of these light sources flicker at twice the mains supply frequency. So a fluorescent lamp on a 60Hz circuit will have a 120Hz flicker. LED lamps using PWM drivers will flicker at the PWM frequency.

For more information, see:
https://www.energy.gov/sites/prod/files ... ller_0.pdf

adafruit_support_bill
 
Posts: 82098
Joined: Sat Feb 07, 2009 10:11 am

Re: Flicker Detection using ams AS7341

by ashish_ash on Sun Sep 26, 2021 3:50 am

Thanks. Now I got an insight and a little understanding about Light flickering.
It seems that the Adafruit ams AS7341 sensor has an On-board LED . I could not find the spectrum of On-board LED. I assume that the LED spectrum provided in the ams AS7341 datasheet is for EVAL Kit and not for Adafruit circuit board. Where can I find the spectrum of On-board LED used?

ashish_ash
 
Posts: 2
Joined: Mon Jun 07, 2021 1:02 pm

Re: Flicker Detection using ams AS7341

by adafruit_support_bill on Sun Sep 26, 2021 7:04 am

It is an EAHC2835WD6 from Everlight. Here is the datasheet:
https://www.mouser.com/datasheet/2/143/ ... 931431.pdf

adafruit_support_bill
 
Posts: 82098
Joined: Sat Feb 07, 2009 10:11 am

Please be positive and constructive with your questions and comments.


cron