Raspbery pi

General notes on some of my Pis

Prep work for power monitoring using lechacal Hats....

Run the raspi-config tool
$ sudo raspi-config

Then disable the login uart
3 Interface Options     <<-- Use option 5 Interfacing Options instead if using the image before 12 DEC 2020
P6 Serial
Would you like a login shell to be accessible over serial?
Select No to the login shell question.
Would you like the serial port hardware to be enabled?
Select Yes to the serial port hardware to be enabled question.

Select Ok at the summary.

Back at the menu select finish.

Would you like to reboot now?
Select No to the reboot question (we will do that later).

sudo nano /boot/config.txt

At the end of the file add the following line:

dtoverlay=disable-bt

sudo systemctl disable hciuart

sudo reboot & exit

Testing that it works

chubbard@power01:~$ cat /dev/ttyAMA0
11 1129.3 62.6 206.0 79.3 2583.9 986.6 246.9 92.4
11 1142.2 60.3 207.3 78.5 2576.7 1028.9 244.9 91.0
11 1134.1 66.0 208.5 75.3 2595.9 1014.4 244.8 90.8
11 1134.4 62.8 206.0 76.7 2566.3 987.1 248.9 91.8
^C

Script currently in use:

#!/bin/bash
# Output from serial port:
# 11 125.7 54.2 51.2 54.5 260.2 58.8 1447.0 53.0

getdata() {
stty -F /dev/ttyAMA0 raw speed 38400 >/dev/null
read ID < /dev/ttyAMA0
echo "${ID}"

# Create array of values:
IFS=$' \r' read -r -a PROBES <<< "${ID}"
unset IFS
}

pushgraphite() {
local G_HOST="192.168.15.193"
local G_PORT=2003

# This is fast so only get the date once
local DAT=$(date +%s --utc)

# Iterate over array of values
for element in "${!PROBES[@]}"; do

  # Suppress the noise floor on the 100A RPICT8 (~59w or so)
  if [[ $( echo "${PROBES[element]} >= 71.9" | bc) -ne 1 ]];then
    VALUE=0.0
  else
    VALUE="${PROBES[element]}"
  fi

  # 0 element is actually the ID of the hat, NOT a valid value
  if [[ ${element} -eq 0 ]]; then
    JUNK=0
  else
    # Send data to Graphite
    if [[ ${UDP} = 'true' ]];then
      echo " monitor.power.probe${element} ${VALUE} ${DAT}" | nc -u -q 1 -C ${G_HOST} ${G_PORT}
      echo "Sent: monitor.power.probe${element} REAL: ${PROBES[element]} SENT: ${VALUE} ${DAT} | nc -u -q 1 -C ${G_HOST} ${G_PORT}"
    else
      echo " monitor.power.probe${element} ${VALUE} ${DAT}" | nc -N -C ${G_HOST} ${G_PORT}
      echo "Sent: monitor.power.probe${element} REAL: ${PROBES[element]} SENT: ${VALUE} ${DAT} | nc -N -C ${G_HOST} ${G_PORT}"
    fi
  fi
done
}

#-------------------------------------------------------------------------------
# Set our defaults
#-------------------------------------------------------------------------------
UDP='false'

# Get any command args for  the script
while getopts "hxU" OPTION
do
  case ${OPTION} in
    h) usage; exit 0       ;;
    x) export PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'; set -x ;;
    U) UDP="true"       ;;
    *) echo "Status WARNING - Unexpected argument given $@"; exit 1 ;;
  esac
done

RES='none'
while [ "${RES}" != 'good' ]; do
  getdata
  # https://www.cyberciti.biz/faq/finding-bash-shell-array-length-elements/
  if [[ ${#PROBES[@]} -ne 9 ]] ; then
    echo "PROBE count ${#PROBES[@]} serial bug detected."
    RES='bad'
    sleep 5
  else
    # echo "PROBE count ${#PROBES[@]}"
    RES='good'
  fi
done

pushgraphite

exit 0