#!/bin/bash
##
# Read a 'USB thermal station' from www.d3p.pl.
#
# This is a USB interface with 8 ports. It responds to commands
# through an ACM driver, which presents as a serial device through
# /dev/ttyACM0 (or possibly higher numbers if you have multiple).
# It requires the Kernel driver 'cdc_acm' to be present on Linux.
#
# Commands accepted by the device are:
#   <digit><return>
#      - report the temperature for sensor <digit> in degrees C
#   V
#      - report the device version
# We only use the sensor commands.
#
# Readings are provided quickly, although I've used a 2 second
# delay here, just to be sure that I get back the data.
#
# The 'cu' tool is used to communicate with the device.
# It is necessary for the device to be accessible by the 'uucp'
# user. You may need to use 'chown uucp /dev/ttyACM0' or similar
# prior to using this script.
#
# Output takes the form of a line per sensor, in the form:
#   id<sensor>=<temperature>
# where <sensor> starts at 0.
#

SENSORS="$1"
DEVICE="$2"
DELAY="$3"
SPEED="$4"

if [ "$SENSORS" = '-h' ] ; then
  echo "Syntax: $0 <sensors> <device> <delay> <speed>"
  echo "  <sensors>    Number of sensors to probe (default 8)"
  echo "  <device>     Device to query (default /dev/ttyACM0)"
  echo "  <delay>      Delay for query (default 2 seconds)"
  echo "  <speed>      Speed to communicate at (default 115200)"
fi

# Set defaults for the paramters
SENSORS=${SENSORS:-8}
DEVICE=${DEVICE:-/dev/ttyACM0}
DELAY=${DELAY:-2}
SPEED=${SPEED:-115200}

# Turn it into a list of sensors
SENSORS=$(seq 0 $(($SENSORS-1)))

# Fire off the request for the sensors - 
( echo $(echo $SENSORS | sed 's/ /\r/g') ; sleep $DELAY ) |
    cu --parity=n -l $DEVICE -s $SPEED dir 2> /dev/null |
    grep id |
    sed 's/ /=/'