DMX Bit-bang Transmitter problem

[dtropman]

Hi all,

I have made a USB-connected bit-bang DMX transmitter using a PIC 18F2550 which produces the data stream perfectly (or so it appears on the scope). I can control all the values using my HID software on the PC and it all runs fine. That is until I connect the RS485 transceiver. I'm using a MAX13082E. Whenever I connect the PIC's DMX output pin (have tried different pins of TTL and Schmitt trigger types, in case that was the problem) to the Transceiver's Datat In pin, the USB enumeration stops and it has even blue-screened my XP PC three times :-(

Can post my code if that would help...?

I'm horribly stuck - help please!!

Thanks in advance,

David

[dtropman]

Hi all - sorry - found that I'd missed the 120R resistor across the transceiver's outputs - wasn't a happy camper. It is now