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[admin]

Update the function once more, it won't spam the log with empty messages.

Code:

function AT:read(timeout)
  local char, err, timeout, deftimeout, line

  -- default timeout is 2 seconds, converted to 0.1 sec ticks
  timeout = tonumber(timeout) or 2
  timeout = timeout * 10

  deftimeout = timeout

  -- read until got one line or timeout occured
  while timeout > 0 do
    -- read 1 char
    char, err = self.port:read(1, 0.1)

    -- got data
    if char then
      -- got LF, end of line
      if char == '\n' then
        -- convert to string and empty buffer
        line = table.concat(self.buffer)
        self.buffer = {}
        line = line:trim()

        -- return only lines with data
        if #line > 0 then
          log('read line', line)
          return line
        -- reset timeout
        else
          timeout = deftimeout
        end
      -- ignore CR
      elseif char ~= '\r' then
        table.insert(self.buffer, char)
      end
    -- read timeout
    elseif err == 'timeout' then
      timeout = timeout - 1
    -- other error
    else
      break
    end
  end

  line = table.concat(self.buffer)
  if #line > 0 then
    log('read timeout', line)
  end

  return nil, err
end

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