ESP32 PICO KIT 4.1 - MTDI Pullup

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ESP32 PICO KIT 4.1 - MTDI Pullup

Postby RobStev0 » Sat Apr 20, 2019 2:04 pm

According to the ESP32-PICO datasheet, the embedded SPI flash requires 3.3V from the internal LDO which would mean MTDI must be held low.

In the PICO Kit schematic available here: ... index.html
...R23 pulls MTDI high, which would force the LDO to 1.8V.

Is this a mistake? If not, what am I missing?

Followup question: Why are the RTS and CTS pins of the CP2104 connected to IO13 and IO15 instead of IO19 and IO22 (which are the correct U0 flow control pins).


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Re: ESP32 PICO KIT 4.1 - MTDI Pullup

Postby ESP_krzychb » Sun Apr 21, 2019 12:37 pm

Hi RobStev0,

NC besides an element on schematic (e.g. R23) means that this element is "not connected".

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Re: ESP32 PICO KIT 4.1 - MTDI Pullup

Postby SomeCallMeTim » Fri Apr 26, 2019 6:46 pm

It's also possible to force 1.8V or 3.3V operation regardless of the MTDI pull status with an eFuse. See ... e-vdd_sdio.

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