Another beginner question from me. Found an old Raspberry Pi model B (the one with two USB ports and the big SD card slot, it says rev 2.0 on the board) in a drawer. I want to reuse it as a simple temperature logger for the boiler room that sends to Hermetry.
Next to the big pin header there’s a row of 8 empty holes marked P5, and near the corner 2 holes marked P6. What are they for? I’d like to add a reset button because the old one hangs sometimes, but I don’t want to fry it by connecting the wrong thing.
I think those are for the camera?
No, the camera is the ribbon connector (CSI) behind the Ethernet port. P5 is extra GPIO I think.
We still have a few of these on line counters, so I’ve been through it.
P6 is the RUN pin. Shorting its two holes resets the board, so solder in two header pins and wire a normal momentary push button across them. That’s your reset button, nothing else needed.
P5 on a rev 2 board is extra power and GPIO:
P5-1 5V P5-2 3.3V
P5-3 GPIO28 P5-4 GPIO29
P5-5 GPIO30 P5-6 GPIO31
P5-7 GND P5-8 GNDGPIO28/29 can be a second I2C bus. It’s meant to be fitted from underneath, so pin numbering looks mirrored from the top, the square pad is pin 1. For a temperature logger you don’t need P5, use the main header (a DS18B20 on GPIO4 is the easy one). Everything is 3.3 V logic, never 5 V into a GPIO.
Put a current Raspberry Pi OS Lite (legacy) on it so the TLS libraries are up to date. Hermetry wants TLS 1.2 or newer with ECDHE suites, and a 2013 image won’t connect.
Button on P6 works, pressed it and the board restarted. Laura was right about the old image, my first attempt was a card from 2014 and the connection failed. New Lite image and it’s sending boiler_temp every minute now. P5 left alone!
- You must be logged in to reply to this topic.
Join the conversation
Sign in to ask and answer, like helpful posts and mark the reply that solved your problem. Every contribution earns points and levels.