How can I convert from 12v serial to 5v serial?

Question

I am attempting to recreate the project detailed here: http://amiga.robsmithdev.co.uk/instructions .

The important part is that a USB FTDI adaptor with the CTS pin broken out is required, and that adaptor will be connected directly to an Arduino. Problem: I don't have such an adaptor. I do, however, have a normal hardware serial port on my computer.

From what I understand, there is nothing stopping me from using this serial port in place of the specced FTDI adaptor, aside from the differing serial signal levels (my computer is likely to have +/-12v, whereas the Arduino is expecting +/-5v.)

So, how can I convert the signal level while maintaining signal integrity at a high serial baudrate (2mbaud is required)?

Answer 1

The signal level must be converted and inversion must take place.

2mbaud is pretty easy (except it's a bit slow for most hardware and firmware), but if you actually meant 2Mbaud, that could be a problem.

There are some transceiver chips such as MAX3245E that can typically reach 2Mbaud with a short cable, but they are guaranteed only for 1Mbaud.

Seems to me like you'd be better off keeping things at TTL level by getting a CH340 or FTDI chip.

Answer 2

There are various ICs that perform this voltage translation--e.g., Texas Instruments MAX232 or similar. Sparkfun, Adafruit, Newegg, and others sell breakout PCBs with these or similar ICs, and a DB9 jack (RS-232), and a 4-pin header for the 5V UART connection.