bash/serial_loopback_test.sh

   1 #!/bin/sh
   2 #
   3 #Serial line tester v0.3
   4 #(c) Tomas Mudrunka 2022-2024
   5 #
   6 #Tested in: busybox ash, bash
   7
   8 function serial_loopback_test() {
   9
  10 trylimit=0
  11 seconds=0
  12 baudrate=115200
  13 workaround_rs485=false
  14
  15 while getopts ":t:r:b:l:s:w" OPT; do
  16         #echo "$OPT ==> $OPTARG";
  17         case $OPT in
  18                 t) port_tx=$OPTARG;;
  19                 r) port_rx=$OPTARG;;
  20                 b) baudrate=$OPTARG;;
  21                 l) trylimit=$OPTARG;;
  22                 s) seconds=$OPTARG;;
  23                 w) workaround_rs485=true;;
  24
  25                 '?') echo "Usage: $0 -t /dev/ttyTX [-r /dev/ttyRX] [-b 9600] [-l 10] [-s 10] [-w]"      >&2; exit 250;;
  26                 ':') echo "Missing option argument for -$OPTARG"                                        >&2; exit 251;;
  27                 *  ) echo "Unimplemented option: -$OPT"                                                 >&2; exit 252;;
  28         esac
  29 done
  30
  31 [ -z "$port_tx" ] && port_tx="$port_rx"
  32 [ -z "$port_rx" ] && port_rx="$port_tx"
  33 [ -z "$port_rx" ] && { echo Port not specified; exit 253; }
  34
  35
  36 testdata="${RANDOM}d82b2ae45432e7c80699852ab557b279c42180a379711aae85487bda0cc58602f65c0ab5af0d510d6ac1606c52f887f3332052f67c45212dbbf2730${RANDOM}"
  37
  38 echo "Running $baudrate baud loopback test on $port_tx -> $port_rx"
  39 echo "Limiting to $trylimit iterations and $seconds seconds (0 = no limit)"
  40
  41 stty -F "$port_tx" raw -echo "$baudrate"
  42 stty -F "$port_rx" raw -echo "$baudrate"
  43
  44 exec 5>"$port_tx"
  45 exec 6<"$port_rx"
  46
  47 $workaround_rs485 && {
  48         echo "Deasserting RTS on buggy RS485 drivers by writing to RX port"
  49         echo>"$port_rx"
  50         read -rst 1 -u 6
  51 }
  52
  53 errcnt=0
  54 trycnt=0
  55 datestart="$(date +%s)"
  56 dateend="$(($datestart+$seconds))"
  57 while true; do
  58         echo "$testdata" >&5
  59         unset line
  60         read -rst 1 -u 6 line
  61         #echo "LINE: $line"
  62         [ "$line" != "$testdata" ] && errcnt=$((errcnt+1)) &&
  63                 echo -e "$(date +'%D %T')\t$errcnt\tError receiving data $port_tx -> $port_rx"
  64         trycnt=$((trycnt+1))
  65         #echo "try $trycnt err $errcnt lim $trylimit"
  66         [ $trylimit -gt 0 -a $trycnt -gt $trylimit ] && break
  67         [ $seconds -gt 0 ] && [ $(date +%s) -gt $dateend ] && break
  68 done
  69
  70 exec 5>&-
  71 exec 6<&-
  72
  73 echo TRANSMITTED: $trycnt, ERRORS: $errcnt, SECONDS: $(($(date +%s)-$datestart))
  74 [ "$errcnt" = "0" -a "$trycnt" -gt 0 ] && exit 0
  75 exit 255
  76
  77 }
  78
  79 serial_loopback_test "$@"