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Thanks for the awesome suggestions. The video port coming out of the Raspberry Pi SoC is HDMI, hence the choice of the connector. We've put the connector on th
by l1k 7y ago
Thanks for the awesome suggestions.
The video port coming out of the Raspberry Pi SoC is HDMI, hence the choice of the connector. We've put the connector on the top of all of our products to lessen the chances of the cable accidentally coming lose. The top and bottom of the case is primarily used for vents. We'd have to make them smaller to fit a VGA or DVI connector there and that might negatively impact heat dissipation. That said, I agree that HDMI is not as rugged. A particular problem we've encountered are cheap cables which connect the shield to ground.
As for flashing the products, there's a micro USB port on the front plate which allows flashing the eMMC from an attached laptop or PC. It's also possible to mount the eMMC to retrieve logfiles from the machine that way. When the machine is booted, it senses whether bus power is provided on the micro USB port. If so, the USB port on the Raspberry Pi SoC is switched to gadget mode instead of host mode. You then need to run a little program called rpiboot on the attached laptop which downloads a firmware to the Raspberry Pi to turn it into a USB Mass Storage Device. Afterwards the eMMC pops up on the attached laptop as an external drive:
https://www.raspberrypi.org/documentation/hardware/computemodule/cm-emmc-flashing.md https://www.raspberrypi.org/documentation/hardware/computemo...
It would in principle be possible to build small gadgets which users plug into the micro USB port and which automatically flash the attached Raspberry Pi without the need for a laptop.
Another possibility would be to split the eMMC into multiple partitions, one containing the regular OS and the other to store an update image. The system would initially boot into a RAM disk, determine whether an update image is present, extract that over the regular OS partition and reboot. The update image could be deployed via ssh.
- LeifCarrotson 7y agoDVI-D has the exact same TDMS signals as HDMI, it just adds optional analog signals (to implement the full DVI-I interface) and drops the CEC remote control interface. I understand the difficulty with keeping the device small! > Another possibility would be to split the eMMC into multiple partitions, one containing the regular OS and the other to store an update image. The system would initially boot into a RAM disk, determine whether an update image is present, extract that over the regular OS partition and reboot. The update image could be deployed via ssh. I'm less concerned about update images and more about backup images. If an update has been created, I'd want to be online with the machine anyways to test the change and I'd have no problem using ssh to develop and deploy. What I'm more concerned about is whether I'm going to get a call from the third-shift maintenance on a Sunday morning if the label printer stops working and the HMI shows "FAULT: Print Computer Watchdog Timeout". I suppose I could create an image that would do nothing but boot from eMMC to a ramdisk, look for a backup image on the micro USB device, and overwrite the eMMC with that image (if found). They couldn't set up a new spare without contacting me, but they could keep that on their shelf...