On Tuesday, January 13, 2026 at 9:19:25 AM UTC-5 Adrian Godwin wrote:

Some RS232 converters are biased to accept TTL, and some USB-serial 
adapters can have inverted data. It's a bodge, but can simplify a board 
made for a specific purpose like these.


Yeah - I took a crash course on the various flavors of serial when I 
started working with the Noritake display...  While *most* devices will 
work with TTL, the bipolar voltages of 'true' RS232 mean that sometimes the 
TTL signals from many usb adapters is seen to be inverted...  After a lot 
of poking around I discovered that FTDI - who is the most prevalent usb 
serial chipset - has a configuration program that allows you to invert any 
pin you want.  That allows common cheap usb adapters to work.  But 
controller projects will need an inexpensive MAX232 adapter to create the 
'correct' voltages.

If you ever need it, you can download the FT_PROG configuration app from 
the FTDI website <https://ftdichip.com/utilities/>.  

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