Question Acer M550 RS232 Control

Discussion in 'Projectors, Screens & Video Processors' started by tvrulesme, Dec 4, 2018.

  1. tvrulesme

    tvrulesme
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    I have an Acer M550 projector as part of my home cinema. I am trying to integrate this projector with my home automation centre (based on hass.io) and the M550 is the only piece in the puzzle which requires IR commands to turn on and off. The off is particularly flaky so I would like to control using RS232 but have run into issues.

    I am using an ubuntu server with a PL2303 which has the following connectors
    Red + 5V
    Black GND
    White RXD
    Green TXD

    I have identified the following pins in my DE-9 connector (assuming the +5V is not required) and have also tried reversing the TxD and RxD

    Screen Shot 2018-12-04 at 05.28.18.png


    The PL2303 is connected and I have read/write permissions on /dev/ttyUSB0
    [ 151.218507] usb 2-3.4.1: pl2303 converter now attached to ttyUSB0
    Having received the command list from here:

    Projector Excel codes

    And setting my tty settings to 9600,8,N,1:
    # stty -F /dev/ttyS0 9600 -parenb cs8 -cstopb -crtscts
    I try this command which should power on the projector
    echo -e "\x2A\x20\x30\x20\x49\x52\x20\x30\x30\x31\x0D" > /dev/ttyUSB0
    And also tried

    echo -e "* 0 IR 001\r" > /dev/ttyUSB0
    But nothing happens. Any ideas where I am going wrong?

    Here is my full stty config:

    stty -F /dev/ttyUSB0 -aspeed 9600 baud; rows 0; columns 0; line = 0;intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V;discard = ^O; min = 0; time = 0;-parenb -parodd -cmspar cs8 hupcl -cstopb cread clocal -crtscts-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff -iuclc -ixany -imaxbel -iutf8-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt -echoctl -echoke -flusho -extproc

    If I use the command

    screen /dev/ttyUSB0 9600

    I get a constant stream of garbage and can't seem to type anything.

    Screen Shot 2018-12-04 at 17.29.29.png
     
  2. steveprior

    steveprior
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    I seem to have missed this question so you have probably fixed this by now.
    If not, this thread has some info that might help:
    Acer M550 Owners Thread

    Short version: it could be a control signal issue, and/or a null-modem is required.
    Does stty -F /dev/ttyS0 9600 -parenb cs8 -cstopb -crtscts set the parameters for /dev/ttyUSB0?

    Longer version: RS232 implementations can vary from really lazy (no flow control or ready signals etc) to strict (all pins must have signals from the other device, so not even tied back) and/or this could be a null-modem problem.

    The thread referenced above suggests some cables to use.
    Typically on a 25-pin RS232 (9-pins have equivalents) you can connect RS232 by wiring (PL2303/PJ) 2/3, 3/2, 4/5, 5/4, 6/8-20 8-20/6, 7/7. IIRC you can tie back 4/5 and 6/80-20. Hence only needing 3 pins.
    This is from memory as I was a comms engineer 30 years ago so Google might be a better friend :)

    Re stty -F /dev/ttyS0 9600 -parenb cs8 -cstopb -crtscts, I don't know if that is a legitimate device or a typo.
     
  3. tvrulesme

    tvrulesme
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    Thanks so much Steve. Actually you helped me out on the Acer M550 Owners Thread above and now works like a charm.
     
  4. steveprior

    steveprior
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    D'oh! I should have checked if it was you :)
     
  5. tvrulesme

    tvrulesme
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    Nah, it was great help. Made some small changes to your python code and in the process of wrapping it all in mqtt. Will post once I'm happy with it all in the other thread. 100% better than my old harmony remote route.....
     
  6. steveprior

    steveprior
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    Perfect. Tbh most (all?) of my scripts are plagiarised from somewhere else, so definitely hacked and worthy of improvement :)
     
  7. tvrulesme

    tvrulesme
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    Coding is all about copy/paste. I'm a Java developer by trade so my python is usually awful.
     

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