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Linux/DLPDLCR2000EVM: Problems with Raspberry system

Ruben Hernandez Garcia
Prodigy 135 points
Part Number: DLPDLCR2000EVM
Other Parts Discussed in Thread: DLP2000, DLPC2607

Tool/software: Linux

Hi!

I connected my Raspberry to the DLPDLCR2000EVM with no problem for an artistic project, following the instructions that I read in the Frederick Vanderbosch website (http://frederickvandenbosch.be/?p=2948), but I need to add an on/safe shutdown button.

After some problems trying to make my own circuit based on internet information, I decided to buy a Witty Pi 2 (http://www.uugear.com/product/wittypi2/). I installed the required software and opened the daemon.sh file that it installs to modify two pins configuration that the DLP2000 need to use. So, I changed the GPIO4 (Halt pin for Witty Pi) and the GPIO17 (LED pin for Witty Pi) to the GPIO27 and GPIO22 that are not going to be used by the projector. If I do a test everything works perfectly. It switches on and do a safe shutdown properly and keeps on doing it when I connect the DLP 2000 to the WittyPi2 (which is connected to the Raspberry). In this case, the projector shows only the splash screen (there is no data sent to it).

When I modify the /boot/config.txt file and the /etc/rc.local file and reboot the system for configure the Raspberry and let it use the projector, the problem appears: the system tries to switch on (you can see the red light in the Raspberry) and the projector shows the splash screen, but suddenly it switches off and you can't see any light in the Raspberry although the WittyPi2 white light is slowly blinking as it usually does when it is in "standby mode". It's like some signal switch off the system while it tries to switch on. You can press again the button for turn it on and the same thing happends.

I'm a newbie in this area and don't know what is happening. Don't know what is going wrong. I were trying to identify what part of the code were responsible of the failure, and I found that in the /boot/config.txt file, there were a line that, if remain commented with the #, let the system to switch on and off, but with no image in the projector. The line appears marked in bold text:

dtoverlay=i2c-gpio,i2c_gpio_sda=23,i2c_gpio_scl=24,i2c_gpio_delay_us=2

# dtoverlay=dpi18
overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
display_rotate=1
framebuffer_width=360
framebuffer_height=640
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87

dpi_output_format=458773
hdmi_timings=854 0 14 4 12 480 0 2 3 9 0 0 0 60 0 32000000 3

Is there anyway to correct the configuration for using that on/off system? It is something indispensable for my project. Would be grateful if I have some help for fixing this system or for knowing an alternative if it's not possible.

Thanks in advance.

Ruben.

  • 0
    TI__Mastermind 28005 points
    Ruben,

    Have you checked if all the power lines on both systems are good? For instance, you should check to ensure that none of the systems are having their supply rails shorted by a ground terminal somewhere else. You should double check all your pin mappings in this case.

    Have you tried using the Witty Pi and the DLP2000 EVM separately first to confirm they both work individually on the PI?

    In addition, you may want to consult the Raspberry Pi community forums for assistance in specifically configuring the Rasperry Pi (once you have confirmed nothing is wrong with your EVM).

    Best Regards,
    Philippe Dollo
  • 0 in reply to Philippe Dollo
    Prodigy 135 points

    Hi, Philippe. Thanks for your response!

    The power lines are good, and there are 5 volts going into the WittyPi2, into the Raspberry and also into the projector when I press the WittyPi2 button for switching the system on.

    I have checked the position of the cables and each one of them are in the correct pin.

    Before I mount the whole system, I checked the Raspberry/projector system (without the WittyPi2) and it worked with no problem. I unmonted then the projector and installed the WittyPi software in the Raspberry. Once installed, I connected the WittyPi to the Raspberry (you have to put it over the Raspberry, it connects by the GPIO pins), and everything worked correctly. I modified the software for using custom pins (GPIO27 and GPIO22) and everything worked correctly.

    The problem comes when I mount the projector connecting the cables to the WittyPi2 that is over the Raspberry and try to switch on the system. Here is a picture with the system mounted:

    https://drive.google.com/file/d/17zsf0BlxfPWnsgEOdzo266r2xyJpYcSX/view?usp=sharing

    As I said, it tries to switch on, but suddenly it switches off. It's like if it receives an orden for shutting down.

    If I put the power cable directly in the Raspberry for a gpio readall, I can see this:

    Don't know what to do.

    Best Regards.

  • 0 in reply to Ruben Hernandez Garcia
    Prodigy 135 points

    As "dtoverlay=dpi18" makes that GPIOs 0~21 are occupied by DPI output, I2C and serial interface will be invalid.

    WittyPi2 uses I2C interface to talk to the RTC chip, and it detects system shutdown by monitoring the serial TXD pin. So, there could be some problems because they are lines that the DLP2000 is using.

    My question is:

    It seems posible to change the I2C pins to other pins, as Philip Hodgers did in his code:

    # Add support for software i2c on gpio pins

    dtoverlay=i2c-gpio,i2c_gpio_sda=23,i2c_gpio_scl=24,i2c_gpio_delay_us=2 
    Is it possible to change the TxD pin (GPIO14) to other of the unused pins GPIO27, GPIO22, GPIO25 and GPIO26?
    Thanks.
    Best regards.
    Ruben.
  • 0 in reply to Ruben Hernandez Garcia
    TI__Mastermind 28005 points
    Ruben,

    Thanks for your patience.

    You cannot change which lines are used by the controller (DLPC2607) for I2C functionality. Any GPIO setup would have to be done on the host side (in this case, the Raspberry Pi).

    Where are you at with this issue?

    Best Regards,
    Philippe Dollo
  • 0 in reply to Philippe Dollo
    TI__Mastermind 28005 points
    Ruben,

    Any updates on this issue? Please reopen this topic by replying if the need arises. Thanks for your attention.

    Best Regards,
    Philippe Dollo
  • 0 in reply to Philippe Dollo
    Prodigy 135 points

    Hi!

    I have tried to do a GPIO setup in the Raspberry Pi for assigning a new pin for the TxD serial connection adding to the config.txt file the following line:

    dtoverlay=uart0,txd0_pin=22

    I have unmounted the Witty Pi 2 and wired it to the Raspberry, while the DLP2000 projector were wired to the Raspberry. But it doesn't work.
    I have read that the pins that you can use for TxD purposes could only be: GPIO14, GPIO32 and GPIO36, as you can see in the BCM manual, page 102:
    As my Raspberry is a 3B+ model and is not a Compute Module (which has more GPIO pins), I only have till the GPIO number 27 and I can't remap TxD pin. 
    So, I'm going to try to connect an USB UART TTL device for trying to assign the TxD to one of the pins that it has and for connecting it to the WittyPi2. I bought the USB TTL device three weeks ago. I hope to receive it soon, but I'm living in northern Africa and shippings delays here easily.
    I will tell you then if I succeed and if so, I'll detail the process to share it with you.
    Thanks.
    Best regards.
    Ruben.
  • 0 in reply to Ruben Hernandez Garcia
    TI__Mastermind 28005 points
    Thank you, Ruben.

    If you have time please share your experience on E2E for the benefit of the community. :)

    Best Regards,
    Philippe Dollo
  • 0 in reply to Philippe Dollo
    Prodigy 135 points
    I will do.
    Thanks to you for your support.