Mike Harsch mharsch

Notes

Trixie doesn't install fake-hwclock by default (no need to remove)
Kernel will pick up rtc time early in the boot process automatically
Supposedly, the kernel watches drift and syncs rtc every 11 minutes
No startup scripts to modify anymore (changed with Trixie)

Setup Procedure

enable i2c using raspi-config
add dtoverlay=i2c-rtc,pcf8523 to /boot/firmware/config.txt
install hwclock by installing the package util-linux-extra

install ModemManager sudo apt install modemmanager
create a new netplan file sudo pico /etc/netplan/modem.yaml Add the following contents:

network:
  version: 2
  modems:
    ttyACM0:
      renderer: NetworkManager
      dhcp4: true

Recent versions of the Raspberry Pi Imager Tool allow customization using cloud-init config and netplan files that are seeded on the boot partition of the sd card as part of writing the image. These files can be edited before booting the pi for the first time, with customizations that will run automatically at first boot.

To automatically pre-configure the pi SD card image for use with the ConnectedIO CM4NA modem, and tailscale do the following:

Prerequisites:

Generate an auth key from the Tailscale Admin Console (Settings -> Keys -> Generate auth key) copy and save for later
Plug in the CM4NA Modem (both data and power) to the Pi. Mode should be AT#USBCFG=0 (default from factory)

Use the latest version of Raspberry Pi Imager tool (ver 2.03 as of this writing)

Uses this container to scrape power data from the reverse-engineered kasa API running on the smart plugs (e.g. HS100).

Docker compose example

compose.yml

version: '3.8'

Most online instructions for Linux watchdog refer to the 'watchdog' package which is best described here

The watchdog configuration described here uses systemd, and the two methods are mutually exclusive, so if you've previously setup the above watchdog, you must first uninstall it.

sudo apt remove watchdog

Our goal is to add a systemd service that continuously pings a known host (or IP address)

	#!/bin/bash

	# Script for wiping old plot directories and prepping drives for new plots
	# Pause between steps in case something goes wrong (Ctrl-C to bail out)
	RANGE=sdb[g-j]

	DEVS=/dev/$RANGE
	DEVS_SCHED=/sys/block/${RANGE}/queue/scheduler
	PARTS=/dev/${RANGE}1
	OLD_DIRS=/plots/${RANGE}1

	This will save you from going down a rather deep documentation rabbit hole:


	1.) enable pcspkr driver by removing blacklist entry for pcspkr in /etc/modprobe.d/blacklist.conf
	2.) create user group 'beep' for controlling permissions to speaker
	sudo addgroup --system beep
	3.) Add your user account to the new beep group (logout and log back in after this step)
	sudo usermod -aG beep $USER
	4.) change default permissions on speaker device to allow members of group 'beep' to access speaker.
	Comment out previous entry and add the following line to /usr/lib/udev/rules.d/70-pcspkr-beep.rules

	/**
	* V. Hunter Adams
	* DDS of sine wave on MCP4822 DAC w/ ISR
	*
	* Modified example code from Raspberry Pi
	* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
	*
	* SPDX-License-Identifier: BSD-3-Clause
	*
	GPIO 8 (pico pin 11) MCP4725 SDA

	RTX 3080 Ti System:
	===================
	OS="Ubuntu 22.04.2 LTS 5.15.0-70-generic"
	SystemVendor/Model="Gigabyte Technology Co., Ltd. B550 AORUS MASTER"
	CPU="1x AMD Ryzen 9 5950X 16-Core Processor (C:16\|T:32)"
	GPU="NVIDIA GeForce RTX 3080 Ti"
	GPUSKU="Ampere"
	GPUArch="N/A"
	DriverVersion="530.30.02"
	PCIeLink="PCIe 4x16"

	#include <math.h>

	// connected to 'D+' pin on mini USB
	const int input_pin = 11;
	// connected to 'D-' pin on mini USB
	const int output_pin = 12;

	void setup() {
	// put your setup code here, to run once:
	Serial.begin(9600);