(Mods if this is the wrong place for this post sorry and please move it).
I ran across a website that has info on using the FTDI USB->serial chip in bit-bang mode http://hackaday.com/2009/09/22/introduction-to-ftdi-bitbang-mode
Anyway, I had been working with a Noritake VFD (vacuum fluorescent display) module that uses the HD44780U command set and has both the standard parallel inputs and also a serial input (not RS-232 serial but an SPI-like serial).
The bulb lit up in my head… bit bang plus SPI serial display = simple display from any USB port!
It turned out to be insanely simple to do. The USB cable with the FTDI breakout board on the other end plugs into the VFD module and even supplies power to it from the USB!
All I need to do is “print” standard input to the little driver program and the display displays it.
With a small BASH script (or a Batch file on Windows) you can read data from your computer (like CPU temperature, HDD free space, whatever), format it and send it to the little display.
I plan to use one to monitor my RAID file server CPU core temperatures and disk free space.
Attached is the source code for it… should anyone be interested. It’s fully commented - should be easy for anyone to compile.
ftdi_to_vfd.zip (3.58 KB)