--
-- Example to read from Quasar Temp Logger.
--
-- This uses luars232 to send to the com port.
--
-- The serial port is buffered.
-- Send the command and wait for PIC to return information.
--
-- Use a simple timeout counter to establish when the PIC has dried up.
--

rs232 = require( "luars232" )

-- Linux
-- port_name = "/dev/ttyS0"

-- Windows
port_name = "COM1"
port_name = "COM3"

local out = io.stderr
lastPort = nil

for cnt = 0,255 do
  port_name = "COM"..cnt
  -- print( port_name )
  local e, p = rs232.open(port_name)
  if e == rs232.RS232_ERR_NOERROR then
	-- handle error
	out:write(string.format("Found serial port '%s', error: '%s'\n",
			port_name, rs232.error_tostring(e)))
     assert(p:close() == rs232.RS232_ERR_NOERROR)
	 lastPort = port_name
  end
end

if lastPort then
  port_name = "COM3"

  -- assume PIC plugged into last port found
  port_name = lastPort
else
  print( "no port found ... ")
end

-- open port
local e, p = rs232.open(port_name)
if e ~= rs232.RS232_ERR_NOERROR then
	-- handle error
	out:write(string.format("can't open serial port '%s', error: '%s'\n",
			port_name, rs232.error_tostring(e)))
	return

end

-- set port settings
assert(p:set_baud_rate(rs232.RS232_BAUD_2400) 	== rs232.RS232_ERR_NOERROR)
assert(p:set_data_bits(rs232.RS232_DATA_8) 		== rs232.RS232_ERR_NOERROR)
assert(p:set_parity(rs232.RS232_PARITY_NONE) 	== rs232.RS232_ERR_NOERROR)
assert(p:set_stop_bits(rs232.RS232_STOP_1) 		== rs232.RS232_ERR_NOERROR)
assert(p:set_flow_control(rs232.RS232_FLOW_OFF) == rs232.RS232_ERR_NOERROR)

out:write(string.format("OK, port open with values '%s'\n", tostring(p)))

print(string.format("OK, port open with values '%s'\n", tostring(p)))


-- read with timeout
local read_len = 1000 -- read one byte
-- local timeout = 100 -- in miliseconds
local timeout = 100 -- in miliseconds

  -- use the read time out to allow the PIC to send response.
  local err, data_read, size = p:read(read_len, timeout)
  assert(e == rs232.RS232_ERR_NOERROR)
  -- print( "===", err,  size )
  -- print( data_read )
  dataBuff = data_read

  -- set buffer and time out
  local read_len = 10000 -- read one byte
  -- local timeout = 100 -- in miliseconds
  local timeout = 5000 -- in miliseconds

finished = 1
silenceCount = 0
dataBuff = ""
while silenceCount < 5 do
  err, data_read, size = p:read(read_len, timeout)
  assert(e == rs232.RS232_ERR_NOERROR)
  -- print( "===", err,  size )
  print( data_read )
  -- print( "+" )
  if  size > 1 then
    dataBuff = dataBuff  ..  data_read
    print("++++", dataBuff )
	finished = false
	finished = dataBuff:len() < 200

	finished = false
	while not finished do
	  --
	  -- look for a line
	  nl, crlf, rest = string.match(dataBuff, "(%C+)(%c+)(.+)" )
	  if crlf then
	    print( "===>", nl , string.byte(crlf,1), string.byte(crlf,2) )
	    dataBuff = rest
	  else
	    finished = true
	  end
    end
  else
    silenceCount = silenceCount + 1
  end

end

assert(p:close() == rs232.RS232_ERR_NOERROR)