I've got an LED sign with an ADSP control board, but the previous owner didn't leave behind the PC interface or remote. I think I've found the tx/rx pins for programming the board, but I need a way to connect this to my computer and it seems like it requires an interface module. Instead of buying a USB-to-db9 cable, I've got some USB to DIP adapters lying around. I'm wondering if I can connect the right pins from the adapter to the RS232 to TTL board. My current plan is to connect Ground to pin 5, D+ to pin 3, and D- to pin 2. Since the MAX3232 board handles the voltage and data conversion, I thought this might work. Just want to make sure I won't damage anything before I try it out!
3 Answers
RS232 and USB are just not compatible at that level. That's why USB to RS232 converters exist. Honestly, you’d be better off using a USB to serial TTL converter directly—going to RS232 first just complicates things and costs more.
Unfortunately, you can't wire it this way. The RS232 and UART are both serial but have different electrical properties. USB doesn’t have TX or RX lines like you're thinking; it uses a bi-directional differential pair. It would actually be much easier and safer to just get a USB to RS232 adapter instead.
Nope! But, you could get a $5 USB-to-UART adapter instead. That would do the job for you without the extra hassle.