Esptool: Add USB-JTAG-Serial reset sequence

esptool.py

@@ -292,6 +292,9 @@ class ESPLoader(object):
  # Response to ESP_SYNC might indicate that flasher stub is running instead of the ROM bootloader
  sync_stub_detected = False
 
+ # Device PIDs
+ USB_JTAG_SERIAL_PID = 0x1001
+
  def __init__(self, port=DEFAULT_PORT, baud=ESP_ROM_BAUD, trace_enabled=False):
  """Base constructor for ESPLoader bootloader interaction
 
@@ -502,7 +505,27 @@ def _setRTS(self, state):
  # request is sent with the updated RTS state and the same DTR state
  self._port.setDTR(self._port.dtr)
 
- def _connect_attempt(self, mode='default_reset', esp32r0_delay=False):
+ def _get_pid(self):
+ if list_ports is None:
+ print("\nListing all serial ports is currently not available. Can't get device PID.")
+ return
+ active_port = self._port.port
+
+ # Pyserial only identifies regular ports, URL handlers are not supported
+ if not active_port.startswith(("COM", "/dev/")):
+ print("\nDevice PID identification is only supported on COM and /dev/ serial ports.")
+ return
+ # Return the real path if the active port is a symlink
+ if active_port.startswith("/dev/") and os.path.islink(active_port):
+ active_port = os.path.realpath(active_port)
+
+ ports = list_ports.comports()
+ for p in ports:
+ if p.device == active_port:
+ return p.pid
+ print("\nFailed to get PID of a device on {}, using standard reset sequence.".format(active_port))
+
+ def _connect_attempt(self, mode='default_reset', esp32r0_delay=False, usb_jtag_serial=False):
  """ A single connection attempt, with esp32r0 workaround options """
  # esp32r0_delay is a workaround for bugs with the most common auto reset
  # circuit and Windows, if the EN pin on the dev board does not have
@@ -527,23 +550,37 @@ def _connect_attempt(self, mode='default_reset', esp32r0_delay=False):
  # DTR & RTS are active low signals,
  # ie True = pin @ 0V, False = pin @ VCC.
  if mode != 'no_reset':
- self._setDTR(False) # IO0=HIGH
- self._setRTS(True) # EN=LOW, chip in reset
- time.sleep(0.1)
- if esp32r0_delay:
- # Some chips are more likely to trigger the esp32r0
- # watchdog reset silicon bug if they're held with EN=LOW
- # for a longer period
- time.sleep(1.2)
- self._setDTR(True) # IO0=LOW
- self._setRTS(False) # EN=HIGH, chip out of reset
- if esp32r0_delay:
- # Sleep longer after reset.
- # This workaround only works on revision 0 ESP32 chips,
- # it exploits a silicon bug spurious watchdog reset.
- time.sleep(0.4) # allow watchdog reset to occur
- time.sleep(0.05)
- self._setDTR(False) # IO0=HIGH, done
+ if usb_jtag_serial:
+ self._setRTS(False)
+ self._setDTR(False) # Idle
+ time.sleep(0.1)
+ self._setDTR(True) # Set IO0
+ self._setRTS(False)
+ time.sleep(0.1)
+ self._setRTS(True) # Reset. Note dtr/rts calls inverted so we go through (1,1) instead of (0,0)
+ self._setDTR(False)
+ self._setRTS(True) # Extra RTS set for RTS as Windows only propagates DTR on RTS setting
+ time.sleep(0.1)
+ self._setDTR(False)
+ self._setRTS(False)
+ else:
+ self._setDTR(False) # IO0=HIGH
+ self._setRTS(True) # EN=LOW, chip in reset
+ time.sleep(0.1)
+ if esp32r0_delay:
+ # Some chips are more likely to trigger the esp32r0
+ # watchdog reset silicon bug if they're held with EN=LOW
+ # for a longer period
+ time.sleep(1.2)
+ self._setDTR(True) # IO0=LOW
+ self._setRTS(False) # EN=HIGH, chip out of reset
+ if esp32r0_delay:
+ # Sleep longer after reset.
+ # This workaround only works on revision 0 ESP32 chips,
+ # it exploits a silicon bug spurious watchdog reset.
+ time.sleep(0.4) # allow watchdog reset to occur
+ time.sleep(0.05)
+ self._setDTR(False) # IO0=HIGH, done
 
  for _ in range(5):
  try:
@@ -578,12 +615,14 @@ def connect(self, mode='default_reset', attempts=DEFAULT_CONNECT_ATTEMPTS, detec
  sys.stdout.flush()
  last_error = None
 
+ usb_jtag_serial = (mode == 'usb_reset') or (self._get_pid() == self.USB_JTAG_SERIAL_PID)
+
  try:
  for _ in range(attempts) if attempts > 0 else itertools.count():
- last_error = self._connect_attempt(mode=mode, esp32r0_delay=False)
+ last_error = self._connect_attempt(mode=mode, esp32r0_delay=False, usb_jtag_serial=usb_jtag_serial)
  if last_error is None:
  break
- last_error = self._connect_attempt(mode=mode, esp32r0_delay=True)
+ last_error = self._connect_attempt(mode=mode, esp32r0_delay=True, usb_jtag_serial=usb_jtag_serial)
  if last_error is None:
  break
  finally:
@@ -3747,7 +3786,7 @@ def main(argv=None, esp=None):
  parser.add_argument(
  '--before',
  help='What to do before connecting to the chip',
- choices=['default_reset', 'no_reset', 'no_reset_no_sync'],
+ choices=['default_reset', 'usb_reset', 'no_reset', 'no_reset_no_sync'],
  default=os.environ.get('ESPTOOL_BEFORE', 'default_reset'))
 
  parser.add_argument(