I would like to be able to output 75 digital out signals from the Raspberry Pi. However it has only 26 GPIO pins. Precise timing is not critical as long as it is within 1 second. I need to be able to turn all the signals on or off at the same time, so charlie-plexing won't work.
I'd imagine such a thing would be possible with another module connected by USB but I was wondering if there would be an easier way to do this using the existing hardware?