From 18fb82bd385cdb28b7f8b32b792cff9bfef916ba Mon Sep 17 00:00:00 2001 From: Robert Falkenberg Date: Sun, 2 May 2021 10:21:23 +0200 Subject: [PATCH] Speed up AT command interface (~130 times faster) Previous implementation waits 300ms for response after each command issued. But many commands finish earlier. This patch improves the command execution time by frequently checking for the response to complete (i.e. ends with OK or ERROR), or the occurence of a timeout (default 200ms). Timeout can be adapted per command to support long response times of certain commands like AT+COPS=? (network search) Execution time benchmark (20 AT commands/responses): Previous: 6.010s (100.0%) New code: 0.045s ( 0.7%) Change-Id: I69b1cbc0a20d54791e5800bf27ebafc2c8606d93 --- pySim/transport/modem_atcmd.py | 76 ++++++++++++++++++++++++---------- 1 file changed, 54 insertions(+), 22 deletions(-) diff --git a/pySim/transport/modem_atcmd.py b/pySim/transport/modem_atcmd.py index eef38cb3..43614f1a 100644 --- a/pySim/transport/modem_atcmd.py +++ b/pySim/transport/modem_atcmd.py @@ -32,53 +32,85 @@ class ModemATCommandLink(LinkBase): def __init__(self, device:str='/dev/ttyUSB0', baudrate:int=115200, **kwargs): super().__init__(**kwargs) self._sl = serial.Serial(device, baudrate, timeout=5) + self._echo = False # this will be auto-detected by _check_echo() self._device = device self._atr = None + # Check the AT interface + self._check_echo() + # Trigger initial reset self.reset_card() def __del__(self): self._sl.close() - def send_at_cmd(self, cmd): + def send_at_cmd(self, cmd, timeout=0.2, patience=0.002): # Convert from string to bytes, if needed bcmd = cmd if type(cmd) is bytes else cmd.encode() bcmd += b'\r' + # Clean input buffer from previous/unexpected data + self._sl.reset_input_buffer() + # Send command to the modem - log.debug('Sending AT command: %s' % cmd) + log.debug('Sending AT command: %s', cmd) try: wlen = self._sl.write(bcmd) assert(wlen == len(bcmd)) except: raise ReaderError('Failed to send AT command: %s' % cmd) - # Give the modem some time... - time.sleep(0.3) + rsp = b'' + its = 1 + t_start = time.time() + while True: + rsp = rsp + self._sl.read(self._sl.in_waiting) + if rsp.endswith(b'OK\r\n'): + log.debug('Command finished with result: OK') + break + if rsp.endswith(b'ERROR\r\n'): + log.debug('Command finished with result: ERROR') + break + if time.time() - t_start >= timeout: + log.debug('Command finished with timeout >= %ss', timeout) + break + time.sleep(patience) + its += 1 + log.debug('Command took %0.6fs (%d cycles a %fs)', time.time() - t_start, its, patience) - # Read the response - try: - # Skip characters sent back - self._sl.read(wlen) - # Read the rest - rsp = self._sl.read_all() + if self._echo: + # Skip echo chars + rsp = rsp[wlen:] + rsp = rsp.strip() + rsp = rsp.split(b'\r\n\r\n') - # Strip '\r\n' - rsp = rsp.strip() - # Split into a list - rsp = rsp.split(b'\r\n\r\n') - except: - raise ReaderError('Failed parse response to AT command: %s' % cmd) - - log.debug('Got response from modem: %s' % rsp) + log.debug('Got response from modem: %s', rsp) return rsp - def reset_card(self): - # Make sure that we can talk to the modem - if self.send_at_cmd('AT') != [b'OK']: - raise ReaderError('Failed to connect to modem') + def _check_echo(self): + """Verify the correct response to 'AT' command + and detect if inputs are echoed by the device + Although echo of inputs can be enabled/disabled via + ATE1/ATE0, respectively, we rather detect the current + configuration of the modem without any change. + """ + # Next command shall not strip the echo from the response + self._echo = False + result = self.send_at_cmd('AT') + + # Verify the response + if len(result) > 0: + if result[-1] == b'OK': + self._echo = False + return + elif result[-1] == b'AT\r\r\nOK': + self._echo = True + return + raise ReaderError('Interface \'%s\' does not respond to \'AT\' command' % self._device) + + def reset_card(self): # Reset the modem, just to be sure if self.send_at_cmd('ATZ') != [b'OK']: raise ReaderError('Failed to reset the modem')