Subject: How to use libftdi ftdi_set_bitmode function bitmask ?
Im really new to this sort of usb device developpement and C code
(started yesterday), so my question is probably very low level. Sorry.
I built a small usb prototype based on MM232R
module that lights a LED when PWREN# (12) pin goes low. It well works
when the EEPROM is configured to have this pin switched on PWREN# event.
After that I configured the EEPROM to accept bitbang on this pin (the
3rd of the 4 bits capables to be used as general purpose I/O) in order
to light my LED using a small C program based on libftdi.
So, I tried to use the ftdi_set_bitmode function, but I can't figure
how to set the bitmask.
I would like to change level of the 3rd bit, but I'm messed up with
Sometimes it works, I tried all the bitmasks values from 0x00 to 0xFF
and notices that some works. My LED lights sometimes.
Also I don't really know if I should use the bit as input or output.
To illustrate my problem, I can't understand why the bitmask value 0xA6
lights my LED :
ftdi_set_bitmode(&ftdic, 0xA6, BITMODE_CBUS); // 0xA6 is
and why 0x9A shut it down.
ftdi_set_bitmode(&ftdic, 0x9A, BITMODE_CBUS); // 0x9A is
What bitmasks should I use to change 3rd pin from low to high and high
to low ? input or output ?
I now it's probably more a question of bitmask understanding than a
libftdi problem, but any help or documentation URLs would be
appreciated to understand this part and begin to learn using this
libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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