I’m trying to come up with the correct hardware I need for my dash project and I’m looking at either the vim3 or the edge+captain. This is essentially the screen size I need https://smile.amazon.com/dp/B07R4VR9PR/ref=cm_sw_r_sms_api_glt_fabc_WFHP3Y5RE1MW229PQGET but I would like to directly connect the display to the khadas so that I would also have control over the display brightness. Can someone point me in the direction of either a screen that is very close to the same size or somehow to connect this panel to allow for screen brightness control?
I have a VIM3. I would caution you on jumping to it. There are numerous issues.
As for screen brightness, I run that directly from an Arduino, putting out a PWM signal back to the LED inverter.
Do you mind sharing the schematic you’re using with the arduino?
VIM3 has been less than stable, and does a poor job of ‘following’ commands to sleep and wake. Attempts to make it work for a real automotive deployment are difficult, and require a lot of extra monitoring to ensure it sleeps and wakes. Further, often once you put it to sleep, it will trigger itself back awake. Very annoying. There are threads on the Khadas forums about it, and the Khadas people are pretty unwilling to help. The controlling microcontroller that runs the power management runs proprietary code that they will not share or open source.
I will gather some pieces of a schematic, but what you need to know is that you want a 20-100Hz PWM signal, from 0-100%DC, active LOW. I used a 2N2222 (or possibly a 2N3904) to drive it, and it was pretty simple.
You used the 2N2222 to drive the display? I do think I’ll need a schematic of how you did that.
Jus tot drive the input of the brightness control on the LED Inverter board. That is how it is done.
Can you share the schematic you used and the code?
I will try to isolate those bits and post them up later this week.
I have seen those complaints as well, what would you recommend? And that is to get an automotive quality system put together?
FWIW my dash size requires a 12.3" display
Now that the RD folks have begun work on a Linux version, I am trying to find a stable Linux SBC that has good power management. I don’t want some hacked together, and generally unsupported method. Looking for something that operates with a logic state, like an on/off switch, to put a SBC to sleep and wake it up, without the cold boot wait. I have been working on a revision to my Teensy/Arduino interface board for the vehicle side of this, and have not put the time in to finding the ‘ideal’ SBC, yet.
VIM3 runs RD very well. It does a great job. Unfortunately, it’s more or less an Android tablet that you supply a display for. The onboard I/O is not particularly useful for this application, and the power management leaves a lot to be desired.
I put this project on the back burner for a bit due to other issues and upgrades to the car that needed to be completed first not to mention the physical portion of making a mounting option for the dash and display for my Mr2. I plan to get started back on some testing with this to see if the vim3 is the best option. I’m interested in seeing how the Linux version would work over android on the vim3 to see if it might be faster booting and such off of the Emmc.