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esp32 design

Posted: Sat Oct 24, 2020 9:01 pm
by sahar37
in ESP32-S2-SAOLA-1_V1.1_schematic there is DTR and RTS line the goes through bjt's, why we cant connect it directly to the esp32 ?
what is the purpose of that? where is the design notes that tell you do that.
i cant find any information about it.

thank you

Re: esp32 design

Posted: Sun Oct 25, 2020 12:33 pm
by ESP_Sprite
It's the auto-reset-circuit, it's been around ever since the ESP8266 was out... the idea is that you can use both lines to reset the ESP32 and put it into flash mode. From memory, the 2 BJTs are there because some (most?) terminal programs will set these lines to both low, and without the BJTs this would lead to no output from the ESP32 as it's kept in reset.