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RPi 3 B+ with Sense Hat getting "Error: cannot open framebuffer device." from snake.c example

osenjw

I am new to RPi.

 

I placed the sense hat on an RPi 3B+ and get a nice rainbow display on the LED.

 

When I run the snake example, I get the message "Error: cannot open framebuffer device."

 

I run in debug using Code::Blocks, and I see that the code apparently finds the joystick.  So the frame buffer is not the first thing I checked.

 

My RPi is nearly virgin.  I have installed Code::Blocks and the sense hat.  Raspian is up to date.  I enabled VNC, SSN, SPI and I2C.

 

I am working headless via a VNC window in W10.

 

Is there an incompatibility between a RPi 3B+ and the sense hat?  I am seeing that it is compatible with RPi 3B  (no +).

 

If not, would somebody offer a suggestion for getting snake to get past this error?

 

Thanks.

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  • Hi John,

     

    Just to confirm, the Sense HAT was placed on the Pi unpowered, right? I doubt the framebuffer appears except at boot time.

    Since i2cdetect seems to be providing the correct type of info, it is likely that the Sense HAT works (but as mentioned, the framebuffer may not appear without a reboot).

    There could be a software issue too - perhaps it is looking for a particular enumeration, and using VNC may be confusing it.

    You could try the following combinations:

    1. Using a HDMI monitor and the Sense HAT

    2. Using the Sense HAT but no HDMI monitor, and no VNC either (i.e. just using SSH).

    The Pi is just a Linux computer - there should be some training material on the Pi website which may make some assumptions (e.g. locally attached HDMI monitor)

    If you're going to create your own procedures, then you have to test it out thoroughly beforehand - the same applies with any STM discovery board too I imagine.

     

    By the way, if this is for students to learn embedded programming, you may need to have someone experienced in troubleshooting nearby, because the engineering-minded/curious students will likely do stuff on their own enterprise, so you'll need to be prepared for that, if they get stuck - that's just the way engineering-minded students are.

     

    EDIT: Reading some more of the posts above, it seems you have rebooted and tried a HDMI monitor. Just to confirm, you're using the 'official' PSU, right? The sense HAT may consume a fair amount of power for the LEDs.

    I have a Sense HAT somewhere so I will try to replicate it if I can find it..

Reply

  • Hi John,

     

    Just to confirm, the Sense HAT was placed on the Pi unpowered, right? I doubt the framebuffer appears except at boot time.

    Since i2cdetect seems to be providing the correct type of info, it is likely that the Sense HAT works (but as mentioned, the framebuffer may not appear without a reboot).

    There could be a software issue too - perhaps it is looking for a particular enumeration, and using VNC may be confusing it.

    You could try the following combinations:

    1. Using a HDMI monitor and the Sense HAT

    2. Using the Sense HAT but no HDMI monitor, and no VNC either (i.e. just using SSH).

    The Pi is just a Linux computer - there should be some training material on the Pi website which may make some assumptions (e.g. locally attached HDMI monitor)

    If you're going to create your own procedures, then you have to test it out thoroughly beforehand - the same applies with any STM discovery board too I imagine.

     

    By the way, if this is for students to learn embedded programming, you may need to have someone experienced in troubleshooting nearby, because the engineering-minded/curious students will likely do stuff on their own enterprise, so you'll need to be prepared for that, if they get stuck - that's just the way engineering-minded students are.

     

    EDIT: Reading some more of the posts above, it seems you have rebooted and tried a HDMI monitor. Just to confirm, you're using the 'official' PSU, right? The sense HAT may consume a fair amount of power for the LEDs.

    I have a Sense HAT somewhere so I will try to replicate it if I can find it..

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