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Purchased FTDI's FT231XS from DigiKey I can see data from the ESP32 microcontroller but when I try to write to it, esptool just says connecting and nothing happens. I can use a usb to serial cable to write so I know the microcontroller is entering programming mode. I have verified continuity on ESP_EN and PROG pins. Not sure if this is a DTS/RTS issue or something else. Any help would be appreciated, I have attached schematic and layout.

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  • \$\begingroup\$ can you show the complete schematic? because right now it looks like your board is missing the ESP_EN pull up part. Which is your reference design? Something like this comparing your schematic with dl.espressif.com/dl/schematics/ESP32-Core-Board-V2_sch.pdf ? \$\endgroup\$ – Christian B. May 11 at 8:19
  • \$\begingroup\$ Schematic is in several sheets on kicad, so there isn't one big sheet. I have pullups on ESP_EN and PROG. I'm able to program by using external usb-uart cable and bypassing ftdi chip. So I know I'm entering program mode and pullups are okay. \$\endgroup\$ – physiii May 11 at 12:41
  • \$\begingroup\$ The schematic you linked to has a 470 ohm resistor (R3) between TX on the USB chip and RX on the ESP32, wonder if that's it? Also, the schematic shows an NPN transistor (Q1) and PNP transistor (Q2) however the part numbers are for the same NPN transistor (S8050) so should I be using an NPN transistor for both on mine too? \$\endgroup\$ – physiii May 11 at 12:52
  • \$\begingroup\$ Well the reason for the 470 Ohm is mostlikely the same why they put this fishy voltage devider into the VBUS supply of the CP2104 on this schematic: dl.espressif.com/dl/schematics/… - to make sure that not a 5V signal from the TX fries the 3.3V RX input of the ESP32. Looking at the true table given in the schematics I would say: yes both have to be NPNs. If you have a scope you could check if the truth table of your circuit matches the expected values given in their schematics. \$\endgroup\$ – Christian B. May 11 at 13:44

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