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 port_tx=
  11 port_rx=
  12 trylimit=0
  13 seconds=0
  14 baudrate=115200
  15 workaround_rs485=false
  16
  17 while getopts ":t:r:b:l:s:w" OPT; do
  18         #echo "$OPT ==> $OPTARG";
  19         case $OPT in
  20                 t) port_tx=$OPTARG;;
  21                 r) port_rx=$OPTARG;;
  22                 b) baudrate=$OPTARG;;
  23                 l) trylimit=$OPTARG;;
  24                 s) seconds=$OPTARG;;
  25                 w) workaround_rs485=true;;
  26
  27                 '?') echo "Usage: $0 -t /dev/ttyTX [-r /dev/ttyRX] [-b 9600] [-l 10] [-s 10] [-w]"      >&2; return 250;;
  28                 ':') echo "Missing option argument for -$OPTARG"                                        >&2; return 251;;
  29                 *  ) echo "Unimplemented option: -$OPT"                                                 >&2; return 252;;
  30         esac
  31 done
  32
  33 [ -z "$port_tx" ] && port_tx="$port_rx"
  34 [ -z "$port_rx" ] && port_rx="$port_tx"
  35 [ -z "$port_rx" ] && { echo Port not specified; return 253; }
  36
  37
  38 testdata="${RANDOM}d82b2ae45432e7c80699852ab557b279c42180a379711aae85487bda0cc58602f65c0ab5af0d510d6ac1606c52f887f3332052f67c45212dbbf2730${RANDOM}"
  39
  40 echo "Running $baudrate baud loopback test on $port_tx -> $port_rx"
  41 echo "Limiting to $trylimit iterations and $seconds seconds (0 = no limit)"
  42
  43 stty -F "$port_tx" raw -echo "$baudrate"
  44 stty -F "$port_rx" raw -echo "$baudrate"
  45
  46 exec 5>"$port_tx"
  47 exec 6<"$port_rx"
  48
  49 $workaround_rs485 && {
  50         echo "Deasserting RTS on buggy RS485 drivers by writing to RX port"
  51         echo>"$port_rx"
  52         read -rst 1 -u 6
  53 }
  54
  55 errcnt=0
  56 trycnt=0
  57 datestart="$(date +%s)"
  58 dateend="$(($datestart+$seconds))"
  59 while true; do
  60         echo "$testdata" >&5
  61         unset line
  62         read -rst 1 -u 6 line
  63         #echo "LINE: $line"
  64         [ "$line" != "$testdata" ] && errcnt=$((errcnt+1)) &&
  65                 echo -e "$(date +'%D %T')\t$errcnt\tError receiving data $port_tx -> $port_rx"
  66         trycnt=$((trycnt+1))
  67         #echo "try $trycnt err $errcnt lim $trylimit"
  68         [ $trylimit -gt 0 -a $trycnt -gt $trylimit ] && break
  69         [ $seconds -gt 0 ] && [ $(date +%s) -gt $dateend ] && break
  70 done
  71
  72 exec 5>&-
  73 exec 6<&-
  74
  75 echo TRANSMITTED: $trycnt, ERRORS: $errcnt, SECONDS: $(($(date +%s)-$datestart))
  76 [ "$errcnt" = "0" -a "$trycnt" -gt 0 ] && return 0
  77 return 255
  78
  79 }
  80
  81 serial_loopback_test "$@"