Search found 108 matches
- Thu Feb 11, 2021 10:20 pm
- Forum: Hardware
- Topic: Power supply schematic
- Replies: 6
- Views: 525
Re: Power supply schematic
It may be better to use a 5V plug-in power supply instead of the item from Farnell and to use a 3.3V voltage regulator such as this example. Then you will simply need 2 capacitors and a barrel socket. This would avoid hazardous mains voltage.
- Mon Dec 16, 2019 1:17 pm
- Forum: General Discussion
- Topic: ADC speed?
- Replies: 28
- Views: 42031
Re: ADC speed?
I tried running the example program of peripherals/adc and found that each conversion took about 40us. That mean, a sampling speed of 25K Samples/second. Is that really possible or I am being mistaken? As reported in an earlier post in this thread, I have measured 9.5μs (including the time taken to...
- Mon Oct 08, 2018 11:05 pm
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
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...
- Sat Oct 06, 2018 4:48 pm
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
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...
- Sat Oct 06, 2018 9:53 am
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
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...
- Fri Oct 05, 2018 6:14 pm
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
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...
- Fri Oct 05, 2018 4:47 pm
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
Re: Bad readings from ADC
Thanks for the suggestion. With 10ms in the loop, I still get a similar spread of rogue readings.fly135 wrote:Try putting a delay between readings.
- Fri Oct 05, 2018 10:53 am
- Forum: General Discussion
- Topic: Dev Kit C without the external pins
- Replies: 2
- Views: 2064
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.
Alternatively, shorten the pins using side (diagonal) cutters.
- Fri Oct 05, 2018 10:10 am
- Forum: General Discussion
- Topic: Bad readings from ADC
- Replies: 10
- Views: 8397
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 ...
- Sun Sep 16, 2018 10:34 am
- Forum: General Discussion
- Topic: i2c instability
- Replies: 9
- Views: 7239
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
https://github.com/stickbreaker/arduino ... aries/Wire