Search found 106 matches

by Archibald
Mon Oct 08, 2018 11:05 pm
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Re: Bad readings from ADC

Could be induced voltage on the connection between pot and pin. Put a 100nF cap as close as possible to pin and ground and use exponential filtering in software. Thanks, but as I get readings from a potentiometer on an Arduino Micro that only vary between adjacent values, I don't think induced volt...
by Archibald
Sat Oct 06, 2018 4:48 pm
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Re: Bad readings from ADC

For realy serious ADC performance analyzes you should use some precision voltage reference source, not the potentiometer which can introduce errors by itself. Thanks for your comment. Voltmeter readings indicate that the ADC input voltage is stable to within 1mV over several hours. With no delay in...
by Archibald
Sat Oct 06, 2018 9:53 am
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Re: Bad readings from ADC

The bottom line is that I don't know what to expect for noise with a measurement like you are doing. For a good ADC with constant input voltage we should expect successive digital readings to either remain constant or to waver between two adjacent digital values. The digital readings can reasonably...
by Archibald
Fri Oct 05, 2018 6:14 pm
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Re: Bad readings from ADC

How are you powering the pot? Are you using a separate regulated supply? I also see a lot of noise on the ADC. So what you are seeing (<3%) isn't that bad compared to what I'm seeing. Although I'm reading a sensor with a lot of amplification. I'm powering the development board and pot by a 5V switc...
by Archibald
Fri Oct 05, 2018 4:47 pm
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Re: Bad readings from ADC

fly135 wrote:Try putting a delay between readings.
Thanks for the suggestion. With 10ms in the loop, I still get a similar spread of rogue readings.
by Archibald
Fri Oct 05, 2018 10:53 am
Forum: General Discussion
Topic: Dev Kit C without the external pins
Replies: 2
Views: 251

Re: Dev Kit C without the external pins

I have removed similar header pins from an Arduino one at a time using a soldering iron. The plastic melts sufficiently. I was holding the Arduino in a small vice along its sides and pulling each pin out with pliers.

Alternatively, shorten the pins using side (diagonal) cutters.
by Archibald
Fri Oct 05, 2018 10:10 am
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 737

Bad readings from ADC

Having noticed a few ADC readings outside the well-known 'noise', I decided to plot a histogram of readings . . . ADC-histogram1.png The x-axis is for readings from 1960 to 2070, not as labelled. The mode (most frequent reading) is at a 2015 so is close to middle of the ADC's range (0 to 4095). The ...
by Archibald
Sun Sep 16, 2018 10:34 am
Forum: General Discussion
Topic: i2c instability
Replies: 9
Views: 2288

Re: i2c instability

There's an alternative Arduino-ESP32 'Wire' library here that is supposed to be better:
https://github.com/stickbreaker/arduino ... aries/Wire
by Archibald
Tue Sep 11, 2018 8:36 am
Forum: General Discussion
Topic: ESP32 AnalogRead()
Replies: 3
Views: 531

Re: ESP32 AnalogRead()

Pin 25 with LEDC is a digital output with PWM (pulse width modulation): https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/ledc.html For an analogue output, use DAC (digital-to-analogue converter): https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/perip...
by Archibald
Tue Sep 11, 2018 3:02 am
Forum: General Discussion
Topic: ESP32 AnalogRead()
Replies: 3
Views: 531

Re: ESP32 AnalogRead()

What do you have connected to pin 36?

Go to advanced search