Hi Wolfram,

downloaded your code and tried it out. The code compiles ok ,but when flashing and monitoring it gives me the following errors. I have GDBstub enabled.

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ESP_ERROR_CHECK failed: esp_err_t 0xffffffff (ESP_FAIL) at 0x40086458
0x40086458: _esp_error_check_failed at /home/patrick/esp/esp-idf/components/esp32/panic.c:724

file: "/home/patrick/esp/sht21/main/main.c" line 41
func: sht21_register
expression: i2c_master_cmd_begin(port, h, 1000 / portTICK_RATE_MS)

ELF file SHA256: 01751c59776f0d17ea72f11b46e19733445d8fd9eb7c5cf9f42fe1e1d0c59ba0

Backtrace: 0x40085ec9:0x3ffb5570 0x4008645b:0x3ffb5590 0x400d23f4:0x3ffb55b0 0x400d261f:0x3ffb55d0 0x400d0c6e:0x3ffb5600 0x40088d45:0x3ffb5620
0x40085ec9: invoke_abort at /home/patrick/esp/esp-idf/components/esp32/panic.c:719

0x4008645b: _esp_error_check_failed at /home/patrick/esp/esp-idf/components/esp32/panic.c:725

0x400d23f4: sht21_register at /home/patrick/esp/sht21/main/main.c:41 (discriminator 1)

0x400d261f: app_main at /home/patrick/esp/sht21/main/main.c:96

0x400d0c6e: main_task at /home/patrick/esp/esp-idf/components/esp32/cpu_start.c:558

0x40088d45: vPortTaskWrapper at /home/patrick/esp/esp-idf/components/freertos/port.c:403

seems to be issue with the i2c_master_cmd_begin function, which is weird considering that it's part of the library. Can you advise how you are compiling the code , environment details ,and if you have successfully retrieved data from the SHT21 ? thx.