ESP32 PICO KIT 4.1 - MTDI Pullup

RobStev0
Posts: 1
Joined: Sat Apr 20, 2019 1:40 pm

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: https://docs.espressif.com/projects/esp ... 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).

Cheers.

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krzychb
Posts: 232
Joined: Sat Oct 01, 2016 9:05 am
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Re: ESP32 PICO KIT 4.1 - MTDI Pullup

Postby 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".

SomeCallMeTim
Posts: 3
Joined: Fri Sep 01, 2017 3:50 pm

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 https://github.com/espressif/esptool/wi ... e-vdd_sdio.

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