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serial: Add Fysetc Cheetah board specific reset sequence

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Fysetc Cheetah v1.2 boards require a special sequence to reset reliably.
This sequence works for me in all cases. Simpler sequences without
double reset did not work correctly. This is likely because of a weird
stateful circuitry for toggling the bootloader state.

Cheetah boards use RTS to configure bootloader triggering. By default,
pySerial sets RTS on connect, which unfortunately configures the board
to start the bootloader on reset.

Add a toggle for the RTS state to allow users to workaround. The RTS state
is set before the serial connection is opened, so there are no glitches.

Addresses #2026.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
This commit is contained in:
Grigori Goronzy 2020-04-01 23:52:55 +02:00 • committed by KevinOConnor
parent 5c8d15bbee
commit 0a20430e07
3 changed files with 56 additions and 13 deletions
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34
klippy/serialhdl.py
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@ -13,12 +13,13 @@ class error(Exception):
class SerialReader:
BITS_PER_BYTE = 10.
def __init__(self, reactor, serialport, baud):
def __init__(self, reactor, serialport, baud, rts=True):
self.reactor = reactor
self.serialport = serialport
self.baud = baud
# Serial port
self.ser = None
self.rts = rts
self.msgparser = msgproto.MessageParser()
# C interface
self.ffi_main, self.ffi_lib = chelper.get_ffi()
@ -85,7 +86,10 @@ class SerialReader:
try:
if self.baud:
self.ser = serial.Serial(
self.serialport, self.baud, timeout=0, exclusive=True)
baudrate=self.baud, timeout=0, exclusive=True)
self.ser.port = self.serialport
self.ser.rts = self.rts
self.ser.open()
else:
self.ser = open(self.serialport, 'rb+')
except (OSError, IOError, serial.SerialException) as e:
@ -266,6 +270,32 @@ def stk500v2_leave(ser, reactor):
logging.debug("Got %s from stk500v2", repr(res))
ser.baudrate = origbaud
def cheetah_reset(serialport, reactor):
# Fysetc Cheetah v1.2 boards have a weird stateful circuitry for
# configuring the bootloader. This sequence takes care of disabling it for
# sure.
# Open the serial port with RTS asserted
ser = serial.Serial(baudrate=2400, timeout=0, exclusive=True)
ser.port = serialport
ser.rts = True
ser.open()
ser.read(1)
reactor.pause(reactor.monotonic() + 0.100)
# Toggle DTR
ser.dtr = True
reactor.pause(reactor.monotonic() + 0.100)
ser.dtr = False
# Deassert RTS
reactor.pause(reactor.monotonic() + 0.100)
ser.rts = False
reactor.pause(reactor.monotonic() + 0.100)
# Toggle DTR again
ser.dtr = True
reactor.pause(reactor.monotonic() + 0.100)
ser.dtr = False
reactor.pause(reactor.monotonic() + 0.100)
ser.close()
# Attempt an arduino style reset on a serial port
def arduino_reset(serialport, reactor):
# First try opening the port at a different baud