GPIO15 as CS in ANNEX32-Doku

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PeterN

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Feb 2, 2021, 3:57:28 PM2/2/21
to Annex WiFi RDS
Good evening CiccioCB

As the ESP32 GPIO15 must be HIGH at boot, it seems to be very important to pull this pin up  if GPIO15 is connected to any  external  medium or low resistance circuit that may draw it down at boot time.  Otherwise the ESP32 can not start. 
I had this problem e.g. when connecting a MAX7219-dot-matrix-display  to an ESP32 devkit V4      

There are some example circuits in the ANNEX32 help file using GPIO15 as the CS (ChipSelect) without an additional pullup resistor.. 

I suggest adding a pullup resistor  of 10K in the documentation to insure the functionality.

Peter

cicciocb

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Feb 4, 2021, 9:46:22 AM2/4/21
to Annex WiFi RDS
HI Peter,
I'll add a note in the documentation or I could just change the pin in the schematic :-)

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