Flickering issue

[pki791]

Hi.

I have connected an ESP32C3 to the LED Panel.

To compile proper it was needed to add the partitions in platformoi.ini

board_build.partitions = partitions-4MB.csv

Also a small fix in the screen.cpp was needed becuase of that pins not exists in the C3 version. We can use -1 to tell the function not to use that pins, that can be helpfull in the 8266 version.

SPI.begin(PIN_CLOCK, -1, PIN_DATA, -1); // SCLK, MISO, MOSI, SS

Now the problem, if the brightness is set to max (100%) the screen is not updating, it stats to work proper when the brightness is about 97%. Depending on the brightness setting and plugin some pixels flicker more or less.

I even updated to use the hardware PWM of the C3 using
ledcWrite(PWM_CHANNEL, 255 - brightness);

Depending in the set frequency it help a little but not really solve the issue.

I already aded some capacitors on the power input, that also not solved it.

Any more ideas?

[pki791]

I solved the issue, at least to a level i think its good.

• added capacitor of 220uF at the SuperMini
• added capacitor of 220uF at the place where the original USB cable powers the board
• changed the short wires from LED board to ESP to 20AWG (0,5mm2)
• the USB power cable connected to the ESP board, not to the LED board
• changed the brightness driver as below

I think the problem is the power requirement of the ESP32C3 and it needs to be powered directly by a good power source, optimal would be a step down regulator and 12V as external input.

Updates:
in screen.cpp replaced analogWrite(PIN_ENABLE, 255 - brightness); with
if (brightness == 255) brightness = 254; ledcWrite(PWM_CHANNEL, 255 - brightness);

in main.cpp added:
#include "driver/ledc.h"

and after pinMode lines:
ledcAttach(PIN_ENABLE, PWM_FREQUENCY, PWM_RESOLUTION);

in constants.h added:
const int PWM_FREQUENCY = 50000; const int PWM_RESOLUTION = 8; const int PWM_CHANNEL = PIN_ENABLE;

That causes to use the hardware PWM present in the newer ESP models to be used instead of analogWrite which additionally reduces the flickering much more.

[pki791]

And again, maybe this needs to be added to the readme, i still had issues, the better USB supply i took so worse it was. So i added a step-down, swapped the cable for 12V, set the step-down at 5.2V and done....so i thought. Probably due to little incompatibilty of 3V3 and 5V devices (ESP32 is 3V3) the voltage needs to be set to 4,7V and now it works very well. Probably also a shoty diode on the supply of the ESP32 board would solve that also. Please add that to the readme, it can save someone much time.