ESP32-C3-01M built in led flashing and serial not working

[sebidani]

Hi!

I recently ordered an esp32-c3-01m kit microcontroller and encountered two issues with it.

I would like to use it to drive a 7-segment display, but I noticed that the display flashes approximately every 2 seconds (there is no delay or serial print in the code). I won't include the code for this because it also causes the LEDs on the board (cold and warm white) to flash simultaneously after a simple digitalWrite turn-on.

The other problem is with the serial monitor.
Previously, with the esp32, I was used to sending debug messages to the serial monitor when it started/restarted, but this does not send anything. Even with the following basic code, I don't get anything when I open the serial monitor:

Code: [Select all] [Expand/Collapse]

1. void setup() {
2.   Serial.begin(115200);
3.   pinMode(18, OUTPUT); //Cold and warm white built in led
4.   pinMode(19, OUTPUT);
5. }
6.  
7. void loop() {
8.   digitalWrite(18, HIGH);
9.   digitalWrite(19, HIGH);
10.   Serial.println("hello");
11.   delay(1000);
12. }

GeSHi © Codebox Plus Extension

The only thing I notice when I open the serial monitor is that all the LEDs on the board turn off, and they turn on again when I close the serial monitor.
For me, Serial is not important for this project, but I thought maybe it's related to the two issues. If the LEDs wouldn't flash, I would be satisfied with it.
Does anyone have any ideas or has anyone experienced something similar?

[ESP_Sprite]

If you're using the built-in USB-serial converter, your use of GPIO18/19 is the issue; these normally are the pins USB is connected to and reconfiguring them will break that connection.

[sebidani]

Thanks for the quick reply. There is a ch340c ic on the board that does the serial-usb conversion. I tried the code pins 18 and 19 excluded, but the same issue.

[ESP_Sprite]

How did you connect the 7-segment display? Are you sure you're not hooking anything up to the ESP TxD0/RxD0 pins?

[sebidani]

Code: [Select all] [Expand/Collapse]

1. #include "SevSeg.h"
2. SevSeg sevseg;
3.  
4. const int dig1 = 9;  
5. const int dig2 = 8;  
6. const int dig3 = 1;  
7. const int dig4 = 0;  
8. const int A = 6;  
9. const int B = 10;      
10. const int C = 5;    
11. const int D = 4;    
12. const int E = 3;    
13. const int F = 2;      
14. const int G = 7;      
15.  
16. int sec = 0;
17. unsigned long preTime = 0;
18.  
19.  
20. void setup() {
21.   byte numDigits = 4;
22.   byte digitPins[] = {dig1, dig2, dig3, dig4};
23.   byte segmentPins[] = {A, B, C, D, E, F, G, -1};
24.   bool resistorsOnSegments = false; // 'false' means resistors are on digit pins
25.   byte hardwareConfig = COMMON_ANODE; // See README.md for options
26.   bool updateWithDelays = false; // Default 'false' is Recommended
27.   bool leadingZeros = false; // Use 'true' if you'd like to keep the leading zeros
28.   bool disableDecPoint = true; // Use 'true' if your decimal point doesn't exist or isn't connected
29.   sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins, resistorsOnSegments,
30.                updateWithDelays, leadingZeros, disableDecPoint);
31.   sevseg.setBrightness(100);
32. }
33.  
34. void loop()
35. {
36.   sevseg.refreshDisplay();
37.   if (millis() - preTime > 1000)
38.   {
39.     sevseg.setNumber(sec);
40.     if (sec != 100) sec++; //count to 100 and stop
41.     preTime = millis();
42.   }
43. }

GeSHi © Codebox Plus Extension

At this code, I stop the counting at 100, and it is clearly visible that the 7-segment display flashes approximately every 2 seconds (which is obviously not caused by the display refreshing since the content is static). I apologize if I worded it ambiguously. I don't intend to use serial communication in the project, I just mentioned it because it doesn't work, and I thought it might be related to the display flashing. The flashing of the display is my main issue.