I'm currently programming an 18f2550 using the usbbootloader.py
running on Debian Linux and using the bootloader autostart code taken
from 18F4550_usb_bootloader_autostart.jal in the "samples" directory.
I have the BOOT_DELAY_IN_SECONDS set to 8.
It will work reliably if I unplug my development board from the
computer, start usbbootloader.py (as root) on my PC, then plug the USB
line from my development board back into the PC while usbbootloader.py
is running.
What I would *like* to do, however, is invoke bootloading from a
switch on the development board while the program on the chip is
running normally. My reset code is simply:
if reset_pin == low then
asm goto 0x000
end if
This will cause the chip to reset and my computer to disconnect the
device & wait the required 8 seconds. However, usbbootloader.py fails
to reprogram the chip, returning:
Traceback (most recent call last):
File "/home/jimg/uc/pic/jallib24/usb_bootloader/UsbBootLoader.py",
line 543, in <module>
print"Boot device version number " +
str( test_loader.WaitForDevice() )
File "/home/jimg/uc/pic/jallib24/usb_bootloader/UsbBootLoader.py",
line 118, in WaitForDevice
usb_driver = UsbBootLoaderDriver()
File "/home/jimg/uc/pic/jallib24/usb_bootloader/
UsbBootLoaderDriver.py", line 93, in __init__
self.device = self.device_descriptor.get_device()
File "/home/jimg/uc/pic/jallib24/usb_bootloader/
UsbBootLoaderDriver.py", line 38, in get_device
buses = usb.busses()
File "/usr/local/lib/python2.6/dist-packages/usb/legacy.py", line
333, in busses
return (Bus(),)
File "/usr/local/lib/python2.6/dist-packages/usb/legacy.py", line
329, in __init__
self.devices = [Device(d) for d in core.find(find_all=True)]
File "/usr/local/lib/python2.6/dist-packages/usb/legacy.py", line
314, in __init__
self.configurations = [Configuration(c) for c in dev]
File "/usr/local/lib/python2.6/dist-packages/usb/core.py", line 723,
in __iter__
yield Configuration(self, i)
File "/usr/local/lib/python2.6/dist-packages/usb/core.py", line 419,
in __init__
configuration
File "/usr/local/lib/python2.6/dist-packages/usb/backend/
libusb10.py", line 471, in get_configuration_descriptor
config, byref(cfg)))
File "/usr/local/lib/python2.6/dist-packages/usb/backend/
libusb10.py", line 403, in _check
raise USBError(_str_error[ret], ret, _libusb_errno[ret])
usb.core.USBError: [Errno 5] Input/output error
I've tried various time delays without success. Does anyone have any
suggestions on how I might be able to make this work?
-Jim
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