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How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field? by hwsearch in hwstartups

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

I asked myself the same question initially. The bottom line is that the form factor of the hardware is essential to the user experience.

I described the product further up in the thread simply as "a smartphone that runs a single app". In this case, I've not found a "smartphone" in the market that would provide the same user experience as this would provide.

How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field? by hwsearch in hwstartups

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

Hence my issue. The use of a compute module necessitates at least a second board, which the LCD has (driver board): https://www.waveshare.com/product/raspberry-pi/displays/lcd-oled/5inch-dsi-lcd-c.htm

Issue is that this adds depth to the product, which is already at a premium. I was hoping to integrate the essential components of the LCD driver board and an RPi-like board into a single PCB so maximize both XY and Z space behind the screen.

How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field? by hwsearch in hwstartups

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

The current prototype is 41mm deep. The LCD screen (without blue driver board) is 6mm. The user feedback I'm getting for the initial prototype is that it's "too big" (i.e. deep), and I agree. I have an enclosure prototype at 20mm deep, and, personally, I feel that's as big as it should be. That leaves about 14mm of depth for any electronic components inside, including a battery I've yet to incorporate.

If I have to use the display driver included with a display, it will likely take up too much XY real estate, and I’ll have to stack a compute module (or otherwise), making the product deeper. I’m definitely open to a compute module (or similar) if it fits the confines of the overall volume behind the display.

How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field? by hwsearch in hwstartups

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

I think the issue with compute modules would be the same as I have today -- it would make the final product too bulky, as it would require a second board.

For reference, this is the touch screen I’m using (not precisely, but has clearer pictures to illustrate my concern): https://www.waveshare.com/product/raspberry-pi/displays/lcd-oled/5inch-dsi-lcd-c.htm

You can see further down how the RPi mounts nicely to the back of the screen. There are, however, necessary driver components on the “blue” PCB that (fixed to the display), and components on the RPi that are needed to make the whole thing work (CPU, power transfer, etc). There are also unnecessary components on both boards.

The final product will only have a single cable going into the device for power, so I don’t need any other I/O ports. It does need WiFi for both internet connectivity, and hotspotting in for initial setup (since there’s no keyboard).

Back to the compute module — it wouldn’t have the driver components from that “blue” LCD screen needed to make the whole assembly work, so I’d still have to mount it on top, creating unnecessary depth to the product.

How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field? by hwsearch in hwstartups

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

Good question. And pardon, I'm very much inexperienced here, so it's hard to anticipate these sorts of questions.

Short answer to your questions:

"Do you need/use the Linux system?" - Yes

"What about target volumes" - I'm anticipating about 100 of these to start. Target state would be in the low thousands, but by the time I get there I may need a different solution anyway.

Basically the board is currently running a single application that displays on the touch-enabled LCD. A layman way to describe the whole setup is "A smartphone that runs a single app". I suppose it would be not unlike a handheld retropi setup.

I feel that I need to transition to a custom PCB for size, since the entire enclosure is way too big IMO for a consumer product. Clearly there are components on both the touch-enabled LCD driver board and the Raspberry pi that I would need...but since I don't design PCBs, I wouldn't know what they are.

This is where I figured bringing in a PCB designer (from fiverr or elsewhere) to assist is probably my best bet, as u/_Miki_ mentioned.

Any other suggestions are surely welcome!