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Author Topic: GPIO15 and ESP8266-EVB-BAT, hardware revision B  (Read 933 times)

Antori91

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GPIO15 and ESP8266-EVB-BAT, hardware revision B
« on: April 30, 2017, 09:05:57 PM »
Hello,
I already did some stuff with ESP8266 and for a new DIY project I'm looking your ESP8266-EVB-BAT product. I've downloaded the schematic, there is a point I can't understand from my previous experience, why GPIO15 is connect to 3.3V via a 47K resistor. I always thought that this pin should be grounded for boot from flash or UART.
Thanks in advance.

LubOlimex

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Re: GPIO15 and ESP8266-EVB-BAT, hardware revision B
« Reply #1 on: May 01, 2017, 09:55:04 AM »
It is already grounded in the design of the small board, that has own schematic here: https://github.com/OLIMEX/ESP8266/blob/master/HARDWARE/MOD-WIFI-ESP8266-DEV/MOD-WIFI-ESP8266-DEV_schematic.pdf

GPIO15 is pulled up mainly to ensure compatibility of ESP8266-EVB-BAT with our extension UEXT modules (sensors and so on). In the UEXT connector GPIO15 acts as chip select for the SPI and it is recommended to have an external pull-up.

Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex