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Bootloader problem
Posted: Thu Jan 10, 2019 8:11 pm
by twiereng
Greetings,
Looks like I've damaged my bootloader on ESP32. How can I re-install the bootloader?
Thanks, Theron Wierenga
Re: Bootloader problem
Posted: Fri Jan 11, 2019 1:41 am
by ESP_igrr
Hi Theron, ESP32 contains a bootloader in mask ROM which can not be damaged or rewritten. Therefore running 'make flash' to program the application (such as a hello_world example) should always succeed. The only case this may not succeed is if some of the Efuses related to flash encryption, secure boot, or SPI flash pins have been burned (programmed). If you can try running 'make flash' for the hello_world example, and post any error output you get, then we can troubleshoot this further.
Re: Bootloader problem
Posted: Fri Jan 11, 2019 2:08 am
by twiereng
Found my problem, I had pin 12 held high.
12 (MTDI) If driven High, flash voltage (VDD_SDIO) is 1.8V not default 3.3V. Has internal pull-down, so unconnected = Low = 3.3V. May prevent flashing and/or booting if 3.3V flash is used and this pin is pulled high, causing the flash to brownout. See the ESP32 datasheet for more details.