tools/pyboard.py: Fix ESPxx boards hanging in bootloader after reset.

Josverl · dpgeorge · commit 9f74ffb6eb8a · 2023-04-04T13:30:05.000+10:00
This is a follow up to d263438, which solved one problem (reset on disconnect) but introduced a second one (hang in bootloader). To solve both probles, False/False is needed for DTR/RTS for ESPxx, but that would then block stm32 and others. Any unconditional combination of DTR/RTS ends up blocking normal operation on some type of board or another. A simple overview (for windows only): DTR CTS ESP8266/ESP32 STM32/SAMD51/RP2040 unspecified unspecified Reset on disconnect OK True False Hang in bootloader OK False False OK No Repl True True Reset on disconnect No Repl False True Reset on disconnect No Repl serial.manufacturer: wch.cn/Silicon Labs Microsoft serial.description: USB-SERIAL CH340 / USB Serial Device CP210x USB to UART Bridge The updated logic will only set the DTR/RTS signals for boards that do not use standard Microsoft drivers (based on the manufacturer). It would also be possible to check against a list of known driver manufactures (like wch.cn or Silicon Labs) but this would require a list of known drivers for all ports. Signed-off-by: Jos Verlinde <jos_verlinde@hotmail.com>
diff --git a/tools/pyboard.py b/tools/pyboard.py
@@ -287,11 +287,15 @@ def __init__(
             for attempt in range(wait + 1):
                 try:
                     if os.name == "nt":
-                        # Windows does not set DTR or RTS by default
                         self.serial = serial.Serial(**serial_kwargs)
-                        self.serial.dtr = True
-                        self.serial.rts = False
                         self.serial.port = device
+                        portinfo = list(serial.tools.list_ports.grep(device))  # type: ignore
+                        if portinfo and portinfo[0].manufacturer != "Microsoft":
+                            # ESP8266/ESP32 boards use RTS/CTS for flashing and boot mode selection.
+                            # DTR False: to avoid using the reset button will hang the MCU in bootloader mode
+                            # RTS False: to prevent pulses on rts on serial.close() that would POWERON_RESET an ESPxx
+                            self.serial.dtr = False  # DTR False = gpio0 High = Normal boot
+                            self.serial.rts = False  # RTS False = EN High = MCU enabled
                         self.serial.open()
                     else:
                         self.serial = serial.Serial(device, **serial_kwargs)
