Closed
Description
Board
ESP32-C3 Supermini (no USB/UART adaptor)
Device Description
ESP32-C3 Supermini is basically an ESP32-C3 chip with a USB-C socket and little else.
https://www.tindie.com/products/adz1122/esp32-c3-development-board-esp32-supermini/
Hardware Configuration
USB-C cable to either a PC (windows 10) or a simple phone charger
Version
v2.0.14
IDE Name
Arduino IDE 1.8.19
Operating System
Windows 10
Flash frequency
80MHz
PSRAM enabled
no
Upload speed
921600
Description
Using "USB CDC on boot : enabled":
If the supermini is powered via a phone charger with no PC connection, Serial.flush() appears to cause a hang.
Sketch
/*
esp32-c3 supermini test
similar to: https://www.tindie.com/products/adz1122/esp32-c3-development-board-esp32-supermini/
set up IDE with
(a) Board ESP32-C3 dev module
(b) "USB CDC on boot : enabled"
(c) JTAG adapter disabled
Test generates lots of serial output and then forces a Serial.flush
This test appears to function correctly whether or not Serial.setTxTimeoutMs(0) is set (but see comment below for case(c)) :
(a) if the supermini is connected via USB to a PC and the serial monitor is active.
(c) if the supermini is powered via a phone charger with no PC connection.
This test appear to work only if Serial.setTxTimeoutMs(0) is set :
(b) if the supermini is connected via USB to a PC and the serial monitor is NOT active.
Serial.flush() appears to cause a hang in case (c)
*/
const uint8_t led = 8 ; // led wired HIGH side
void setup() {
pinMode( led, OUTPUT ) ;
digitalWrite( led, HIGH ) ;
Serial.begin( 115200 ) ;
// only defined if option "USB CDC on boot" selected in IDE
// Serial.setTxTimeoutMs(0) ; // https://github.com/espressif/arduino-esp32/pull/7583
while ( !Serial && millis() < 10000 ) {
delay(500) ;
}
// pulse led for 4 seconds if serial connection found.
if ( millis() < 10000 ) {
Serial.println( "found Serial") ;
digitalWrite( led, LOW ) ;
delay( 4000 ) ;
digitalWrite( led, HIGH ) ;
delay( 1000 ) ;
}
else {
// no Serial found
}
}
void loop() {
for ( int j = 0; j < 10 ; j++ ) {
for ( int i = 0; i < 500 ; i++ ) {
// Serial.print( i ) ;
// Serial.print( '\t' ) ;
// Serial.println( "the quick brown fox jumps over the lazy dog" ) ;
Serial.printf( "%4d \t %s \r\n", i, "the quick brown fox jumps over the lazy dog" ) ;
delay(1) ;
}
digitalWrite( led, LOW ) ;
delay( 1000 ) ;
digitalWrite( led, HIGH ) ;
delay( 1000 ) ;
if ( j == 9 ) {
// this kills it if there is no serial monitor connected
Serial.flush() ;
}
}
}Debug Message
No debug messages with this use case (no serial monitor)
Other Steps to Reproduce
I have checked existing issues, online documentation and the Troubleshooting Guide
- I confirm I have checked existing issues, online documentation and Troubleshooting guide.