Version 1 of apache tcl cgi script with serial port access

by Theo Verelst

I used this test script to drive a serially connected xilinx chip using a apache (2.0 Fedora Core4,64bit) and get 4 bytes of info back from it, it serves as a display and external signal reader/driver.

Basically, its just a cgi program which happens to be a tclsh script:

 #!/bin/sh
 # \
 exec tclsh "$0" "$@"

  # must supply meta type
  puts stdout "Content-type: text/html\n"
  puts stdout "<HTML>"
  puts stdout "<HEAD>"
  puts stdout "<TITLE>Test CGI Tcl script</TITLE>"
  puts stdout "</HEAD>"
  puts stdout "<BODY>"
  puts stdout "Test.\n"

  # open and set up serial port connection
  # possibly use chmod a+rw on it, because this script will be not root
  set fh [open /dev/ttyS0 RDWR]
  # the xilinx demo board I've programmed to have 10kB/s serial connection
  fconfigure $fh -blocking 0 -mode 115200,n,8,1 -translation binary -buffering full

  # put the responses from the board on the page when they come in
  fileevent $fh readable {
    set w [read $fh] ;
    foreach c [split $w {}] {
       binary scan $c H* a; set v $a
       # print in HEX
       puts " $v"
       # flush stdout
    }
  }

  # write a number of bytes to seriap port in binary from from a hex string
  proc w h {
    global fh
    puts -nonewline $fh [binary format H* "$h"] ; flush $fh
  }

  # if any arguments are given to the url, print them
  puts "<P>\n"
  puts "$env(QUERY_STRING)\n<br>\n"

  # send a in this case fixed 4 bytes to the FPGA, which turn on the display here
  w 00000000
  after 1000
  # and another 4 byte data to turn it off
  w 40000000

  puts "</BODY>"
  puts "<HTML>"
  flush stdout

  # make the cgi end after a second
  after 1000 exit
  # meanwhile read the returning data bytes
  while {1} {
    flush $fh
    vwait v
 }

 # should never be needed
 exit

The board:

I'll make the fpga programming file available when I've time, it can set leds, 4 led displays and read switches and communicate at least a 100 or so external signals using the spartan-3, see also

To run the script, put it in /var/www/cgi-bin/test.tcl or where youre apache's cgis are supposed to go, don't forget to make it readable by the servers' uid, and use this url to make it run: http://yourhost/cgi-bin/test.tcl

In my case:

 http://www.theover.org/cgi-bin/test.tcl

assuming the setup is unchanged when you read this. Getting this url will flash the display on the board a few seconds and return the 8 switches setting as one byte of data, example output:

 Test.


 00 52 15 00 40 52 15 00

If anyone's got a good idea they want with this setup, send me a mail, I might make it for them, I'll have some of my own and its a good example. In fact the MSB of the first databyte can put a 20 watt ligthbulb on and off.