Search found 110 matches

by Archibald
Fri Oct 05, 2018 10:10 am
Forum: General Discussion
Topic: Bad readings from ADC
Replies: 10
Views: 20213

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: 14282

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: 18347

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: 18347

Re: ESP32 AnalogRead()

What do you have connected to pin 36?
by Archibald
Tue Aug 21, 2018 7:21 am
Forum: General Discussion
Topic: ESP32 of GPIO
Replies: 1
Views: 3806

Re: ESP32 of GPIO

From the datasheet section 5.3, pull-up resistance is typically 45kΩ. Minumum and maximum values are not specified.

By connecting a resistor to ground and measuring the voltage, I am measuring a pull-up resistance of 23kΩ but that is just for one pin on one ESP32.
by Archibald
Mon Aug 20, 2018 9:43 am
Forum: General Discussion
Topic: I2C Busy Timeout and wedged I2C Bus
Replies: 6
Views: 10295

Re: I2C Busy Timeout and wedged I2C Bus

There have been many reports of problems with I²C failing.

There's an alternative Arduino-ESP32 'Wire' library here that is supposed to be better:
https://github.com/stickbreaker/arduino ... aries/Wire
by Archibald
Sat Aug 18, 2018 7:55 am
Forum: ESP32 Arduino
Topic: What's the advantage of SigmaDelta?
Replies: 9
Views: 15648

Re: What's the advantage of SigmaDelta?

Hi Human, You asked how to do sinusoidal with ESP32 :) . PWM and sigma-delta are digital signals so you need to filter them to get an analogue signal. Using a DAC is very much better but you have only two channels available. The output from a DAC includes some unwanted signal components because the ...
by Archibald
Fri Aug 17, 2018 2:58 pm
Forum: ESP32 Arduino
Topic: What's the advantage of SigmaDelta?
Replies: 9
Views: 15648

Re: What's the advantage of SigmaDelta?

Can you tell me how to do sinusoidal with ESP32? You can include proper ESP32 code in your Arduino code. This code generates a sinusoidal waveform from one of the digital to analogue converters . . . . . extern "C" { #include "dac.h" } float theta; void setup() { dac_output_enable(DAC_CHANNEL_1); /...
by Archibald
Wed Aug 15, 2018 12:06 pm
Forum: ESP32 Arduino
Topic: ESP-Wrover-Kit pin names in Arduino
Replies: 5
Views: 10011

Re: ESP-Wrover-Kit pin names in Arduino

As documented here , pins 34 to 39 can only be set as input mode and do not have software pullup or pulldown functions. Also pins 6-11 are used for the SPI flash memory. Pin 0 (zero) is used by the 'Boot' button. Furthermore from this documentation of the Wrover: "GPIO16 and GPIO17 are used as the C...
by Archibald
Wed Aug 15, 2018 2:51 am
Forum: ESP32 Arduino
Topic: ESP-Wrover-Kit pin names in Arduino
Replies: 5
Views: 10011

Re: ESP-Wrover-Kit pin names in Arduino

I'm using a different kit but simply use the pin numbers in Arduino code, for example:

Code: Select all

pinMode(32,OUTPUT)
digitalWrite(32,LOW);
;