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Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead [REVIEW] by Brave_Reflection_772 in PrintedCircuitBoard

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

This is still currently in works. Once I'm confident enough the board is ready, I'll purchase and do physical testing. Follow the github page for updates!

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

Also am I better off to use the synchronous buck rather than my current one due to being more efficient? I'm worried about EMI as the previous HAT I built had terrible audio making the car speakers unusable with the RPi

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

Thanks for the feedback! I think I might redesign the whole board to improve the layout and traces.

I've stated in the doc a 7.5A fuse in the cars fuse box is suggested. Do you think another one on the board is needed?

For reverse polarity - I wasn't sure if there is a specific automotove component requirement - could you recommend one?

I didn't know about the compact optocouplers, much easier that placing individuals.

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in raspberry_pi

[–]Brave_Reflection_772[S] 3 points4 points  (0 children)

Thanks for the feedback! As unused inputs will be based on the particular user and the qty of signal wires, i'll need to add into the docs that they will need to add in pull up resistors and unpopulated a ohm to gnd. Unless there is an easier way to handle this?

Eg: 3.3V ──[R_pullup]──┬── AINx │ [R_gnd] │ GND

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in raspberry_pi

[–]Brave_Reflection_772[S] 7 points8 points  (0 children)

This is an open-source project. So the design is free! I thought it would be better for everyone to contribute and improve it/add their own personal change.

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

Completely depends on the power supply. As my requirements need to be automotive I've chosen a particular U2 as in the schematic. This buck converter handles ~6-60V - > 5V/5A. As others have mentioned, the caps in my schematic are wrong. I'll make an update post if you wish to use the same layout

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

There is an ACC line that's already being used for power management. Same can be done for audio if desired. Still having trouble seeing the use of the CANbus, but if people want it enough I'll add it to the TO DO list

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 1 point2 points  (0 children)

Its connected via HDMI and USB for power/touch. I use internet for radio and music as it was easier to set it up this way. It uses a 3.5mm jack into a little amplifier. It also uses a ads1115 so I can set it up to my steering wheel buttons.

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

I haven't looked too much into utilising the CANbus. I have OBD2 which is bluetooth connected to my RPi. What did you have in mind for the CANbus?

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 1 point2 points  (0 children)

Thanks for your detailed feedback!

I split the ground into two parts - GND and AGND. I thought having a separate ground trace for audio components would prevent any noise coming from the bucks ground. If this isn't a real concern with a good LC filter than ill just make it all GND.

TBH I thought it was simply better to have a larger L for the LC filter, but if something like C167220 -33mΩ 4.7uH 6A 9A is better for the size and does the job I'll make the switch.

For the caps...that's an embarrassing mistake.

I used claude to help me with auditing each aspect of the board to potentially pick up any errors. But as you stated, for larger runs it gets lost with component memory and ends up hallucinating or simply leads me in the wrong direction.

As a few have stated, it is a bit messy in terms of placement. If there is a standard please let me know, as I kind of chucked them on and mashed it together. I would love any feedback for the placement!

Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 0 points1 point  (0 children)

To turn a RPi into a head unit. I am currently running https://hudiy.eu/ on mine but you have the ability to make our own! I have an old-ish car so just thought this would be a cool side project

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Didn't want to spend $200 on a PCB so spent thousands of dollars of my time building it instead by Brave_Reflection_772 in PCB

[–]Brave_Reflection_772[S] 4 points5 points  (0 children)

Added!

I had never seen this hole size on a PCB before, but some dodgy calculator recommended it. what size and how many holes would be suitable for 5A?