Serial1 communication with projector [Solved]


I’m having trouble communicating over serial with my Viewsonic projector and photon. I have a sparkfun RS232 shifter wired between the projector’s RS232 port and the hardware serial pins on the photon. The documentation is fairly sparse and a bit confusing to me:

Here are the bits of code that I think are relevant. I’m just trying to send the Power On command. The documentation does describe the serial parameters and they are the defaults apart from the baud rate.

byte onMsg[10] = {0x06, 0x14, 0x00, 0x04, 0x00, 0x34, 0x11, 0x00, 0x00, 0x5D};
if (!strcmp(p, "ON")){
   Serial1.write(onMsg, 10);
   RGB.color(0, 255, 0);

I know the photon is sending some signal because a) the led turns green and b) the leds on the RS232 shifter data lines blink.

Am I writing the bytes correctly? Anything else I could be doing wrong? I wish I could test this independently but I don’t have a usb converter laying around.


You may want to test with the default baudrate to start. Also, what kind of cable are you using? A straight through RS232 cable? A Null Model cable? You may need to use the latter.


Documentation lists 115200 as the baud rate, I’ve tried lower with no success. Didn’t think about a cross-over cable, just ordered one. I’m currently using a straight through. Does it look like I’m writing the bytes correctly? That’s something I wasn’t sure about.

Thanks for the help!


@shrimpboat, your write is fine. A Null Modem cable should do the trick.


Finally made it work. Turns out the sparkfun TTL to RS232 converter was not up to the task. Got a different one off amazon and it works a treat.

Thanks for the help!