Search found 31 matches

by HelWeb
Sat Aug 10, 2019 8:20 pm
Forum: General Discussion
Topic: ADC calibration with VREF
Replies: 5
Views: 6764

Re: ADC calibration with VREF

Maybe you may want to test: esp32.com/viewtopic.php?f=19&t=2881&start=30 Posted: Sat Aug 10, 2019 12:30 pm You may calibrate your own ESP32( the nonlinear 11DB curve) with this program.<br> All you need is a wire from pin 25 to pin 35 and a normal voltmeter.<br> Calibration is done automatically.<br...
by HelWeb
Sat Aug 10, 2019 8:11 pm
Forum: General Discussion
Topic: ADC Calibrated Value still not correct?
Replies: 4
Views: 2015

Re: ADC Calibrated Value still not correct?

Maybe you may want to test: esp32.com/viewtopic.php?f=19&t=2881&start=30 Posted: Sat Aug 10, 2019 12:30 pm You may calibrate your own ESP32( the nonlinear 11DB curve) with this program.<br> All you need is a wire from pin 25 to pin 35 and a normal voltmeter.<br> Calibration is done automatically.<br...
by HelWeb
Sat Aug 10, 2019 8:06 pm
Forum: Hardware
Topic: ESP32 ADC Calibration curves?
Replies: 17
Views: 11073

Re: ESP32 ADC Calibration curves?

Maybe you may want to test: esp32.com/viewtopic.php?f=19&t=2881&start=30 Posted: Sat Aug 10, 2019 12:30 pm You may calibrate your own ESP32( the nonlinear 11DB curve) with this program.<br> All you need is a wire from pin 25 to pin 35 and a normal voltmeter.<br> Calibration is done automatically.<br...
by HelWeb
Sat Aug 10, 2019 10:30 am
Forum: ESP32 Arduino
Topic: ESP32 ADC Non-linear Issues - How do I fix / change Attenuation or width?
Replies: 41
Views: 34144

Re: ESP32 ADC Non-linear Issues - How do I fix / change Attenuation or width?

Is it possible to get precise results from ESP32-ADC ? As told we need a LUT for that. I could not resist to do it myself as a proof of concept :D AND FOR ME IT WORKS VERY WELL. This time I estimate the ESP32-DAC produces correct values. ====================== NOTE ==================================...
by HelWeb
Fri Aug 09, 2019 7:54 pm
Forum: ESP32 Arduino
Topic: ESP32 ADC Non-linear Issues - How do I fix / change Attenuation or width?
Replies: 41
Views: 34144

Re: ESP32 ADC Non-linear Issues - How do I fix / change Attenuation or width?

Original_Output.jpg ( for the images 10 bit values are used: DA>>2, AD<<2) I got same strange results like vseven in his first post. I wanted to put DA voltage (8bit) to pin 25 (DAC_CHANNEL_1) and then (pin 25 connected to pin 35) read back the voltage with adcStart(35),adcEnd(35); shifted from 12 ...
by HelWeb
Wed May 01, 2019 4:32 pm
Forum: Sample Code
Topic: Dimming Neopixels, Delays<Microseconds
Replies: 3
Views: 1386

Dimming Neopixels, Delays<Microseconds

Neopixels have great possibilties. With a normal LEDs you can show the state of a system (blue= too cold, red= too hot). With a neopixel you can show values in between with smoothly changing colors from for instance blue ... many colors ... red. Dimming an LED may be done with PWM - not so with a Ne...
by HelWeb
Sun Apr 28, 2019 10:10 pm
Forum: Sample Code
Topic: Sinus Signal Generator from 18Hz to 250kHz
Replies: 2
Views: 1636

Sinus Signal Generator from 18Hz to 250kHz

From this excellent work as base https://github.com/krzychb/dac-cosine I build a signal generator to produce sinus signals from 18Hz to 250kHz. From 50Hz to 100kHz the difference to the wished frequency is about 1% And it works without CPU after initialisation. // Function generator Sin // (C) Helmu...
by HelWeb
Sun Apr 28, 2019 9:35 pm
Forum: General Discussion
Topic: DMA and DAC
Replies: 10
Views: 3084

Re: DMA and DAC

As far as I can see there is only one CW-Generator :x But it would be interesting to get a 2. Channel with DMA output. From this as base https://github.com/krzychb/dac-cosine I build a Sin Function-Generator which delivers frequencies from 18Hz to 250KHz. The frequencies from 50Hz to 100KHz (every v...
by HelWeb
Fri Apr 26, 2019 2:42 am
Forum: ESP32 IDF
Topic: Reduce external interrupt latency
Replies: 12
Views: 3998

Re: Reduce external interrupt latency

I am awaiting a shit storm ;) There are some people trying to start a program without RTOS using core 1. It is not easy. You may think using make menuconfig to set RTOS to core0 and write a function start_cpu1 should do the job - but it does not! If you look at components/esp32/cpu_start.c and compo...
by HelWeb
Mon Apr 22, 2019 7:04 pm
Forum: ESP32 IDF
Topic: Reduce external interrupt latency
Replies: 12
Views: 3998

Re: Reduce external interrupt latency

If you use a one-way-signal as a global variable the communication is much faster. One-Way means Task 1 only writes, Tasks 2 only reads. (volatile). Using this mechanism it is possible to get cycles of 300ns. But there is a drawback: The task in core 0 MUST run without a taskswitch, delay etc. That ...

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