bash/serial_loopback_test.sh

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