Fixes for bitbang mode#431
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November 13, 2025 10:27
When using FTDI as a GPIO adapter in bitbanging mode to control some external hardware, it is highly undesirable to leave ttyUSBn available for opening and possibly ruining the state of output pins. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
The release_interface() called from Ftdi.close() should be matched by claim_interface() in Ftdi.open_from_device(). Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
When using Ftdi.open_bintbang_*() functions, don't reset the bitmode because it causes some pins to twich briefley before the BITBANG mode is set. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
According to libusb documentation [1] it isn't always desirable to call SET_CONFIGURAITON if a device has already been configured. The same approach can be found in libftdi[2]. I have observed that devices didn't work properly in BITBANG mode after the configuration was set to the one the device had alredy been using. [1] https://libusb.sourceforge.io/api-1.0/libusb_caveats.html#configsel [2] http://developer.intra2net.com/git/?p=libftdi;a=blob;f=src/ftdi.c;h=f5b70188f91fc1d4c329d891698ec74566ebeb94;hb=5c2c58e03ea999534e8cb64906c8ae8b15536c30#l631 Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
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These commits fix several problems I had when running an FTDI dongle in BITBANG mode to control external hardware.