Valid pin layout for Heltec WiFi Kit 32 V3

#1

I have seen proper pin layouts for the Heltec WiFi Kit 32 V2 and for the LoRa V3 but only amateurish homemade layouts for the Heltec WiFi Kit 32 V3. These homemade layouts are never consistant and show important pins such as 21, 22, 41,42 in different locations. Where can I find an accurate and if possible official pin layout for the Heltec WiFi Kit 32 V3?

#2

The one on the product page seems OK:

#3

It doesn’t seem OK to me. For instance where are the second I2C bus pins mentioned in the description on that page? And where is pin 15 which is also mentioned in the description?

#4

Something to get our teeth in to …

Per this discussion, the second I2C pins are any that are free - on the ESP you can map pretty much any peripheral to any pin.

On the WiFi, the default pins are set to 21 & 22. The full pin list is here: https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series/blob/master/variants/heltec_wifi_kit_32_V3/pins_arduino.h

I can’t see a pin 15 on the web page or the data sheet. Can you tell me where / what you are looking at?

It’s defined in the Arduino BSP above, but appears to be XTAL_32K_P on the schematic.

This confusing is pretty much standard, so we have to cross reference against the ESP32 docs and so on.

#5

Thanks for the information. I have discovered what my problem is: on my Heltec WiFi Kit 32 V3 the pins 1(Ground) and 2(3.3v) on header J3 are not connected. If I use the pin1 on the header J2 and pin 3 on header J3 for power I can run my sketches using pins 41 and 42 for the I2C. I don’t know if the unconnected pins 1 & 2 on header J3 is a common problem or just a problem with my board.

I was getting very frustrated not being able to get a seocnd I2C working and was looking all over the web, several pages mentioned that the main I2C was on pins 15 and 4 although it is on pins 17 & 18, I guess that is why I was looking for pin 15.

#6

On the WiFi, the default pins are set to 21 & 22.

But there is no GPIO22 pin on the Pinout diagram you linked to in your first reply above. I am used to the ESP32 and ESP8266 and Arduino’s, the product information for those is always very clear. The product information for the Heltec WiFi Kit 32 V3 is often contradictory as this example shows.

#7

Yup, welcome to Heltec, the pins_arduino.h provide a default that doesn’t fit with the schematic, particularly as it shows that pin 21 appears to be the reset for the OLED …