MEWS: Marine Electronics Wiki

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====== Raspberry Pis ======

===== 5 =====
==== Connectors ====

The Pi 5 (and some Picos I think) have a UART connector.
It seems to be a JST SH. The plug is, however, called JST SR. 1mm pitch.

Pi 5 UART max 921,600bps.

The same connector is use on some Picos and the Debug Probe for SWD.

== Pinout ==

| 1 | 2 | 3 |
| RX | GND | TX |
| SWCLK | GND | SWDIO |
USB
[[https://datasheets.raspberrypi.com/debug/debug-connector-specification.pdf]]

===== WiFi =====

Show stations connected to the pi's AP:
''iw dev wlan0 station dump''

===== Power =====

Does not do well on brownout. It didn't come back up when voltage dropped on high resistance cable. I found it with red LED on. Didn't power up properly until replugged, twice. There was also some data loss on the SD card.

According to a forum post, will not power on itself if powered on GPIO pins. It can run, but needs power button pressed.

===== USB =====

==== Power Switching ====

Switches, off then on, power to USB ports. Apparently you can't do them individually, but need to turn them all off to get any of them to go off.

This needs a recent version of uhubctl - the version in Raspbian didn't work. I built from git.

<code bash usb_powercycle>
#!/bin/bash

uhubctl -l 1 -a 0
uhubctl -l 2 -a 0
uhubctl -l 3 -a 0
uhubctl -l 4 -a 0

sleep 3

uhubctl -l 1 -a 1
uhubctl -l 2 -a 1
uhubctl -l 3 -a 1
uhubctl -l 4 -a 1
</code>

===== 3 =====

==== Power ====

Recommended 2.5A supply, but that includes max of 1.2A for USB ports, so 1.3A board. Type 500mA. With LoRa board, maybe 1.5A total needed at 5V.

7.5W.

About 700mA max at 11V - i.e. a nearly empty lead acid battery powering the CAN bus. NMEA micro cables should be 22 AWG for power. ~62R / km, 124R with return. ~1R2 for 10 meters. Seems ok.