Waveshare hardware quality: any experience?

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pythoncoder
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Waveshare hardware quality: any experience?

Post by pythoncoder » Wed Jan 13, 2021 2:23 pm

Blaming hardware is my last call but there seems little doubt that I have encountered two of these e-ink HATs with problems.

I am trying to get nanogui to support at least one ePaper display so I wrote a driver for the board based on that of @mcauser and official Waveshare code. The first unit refused even to clear the display properly and I measured some very suspect logic levels on the board. I figured I'd struck unlucky and bought another from the Waveshare eBay store. I had more success with this one. On occasion the GUI demo programs ran perfectly, but if I left it overnight and ran the same code the next day it failed, sometimes with the weirdest symptoms. For example a display update taking 20 minutes. I could sit at the REPL watching the display faffing about on its own before eventually settling down and releasing the busy signal. Sometimes the display would show interchanged black and white pixels. And so on. The board has no concept of deterministic behaviour :shock:

By contrast I adapted the driver for an Adafruit EPD and barring one typo and one silly bug it worked first time. As always, Adafruit hardware does what it says on the tin :D

I studied the Waveshare boards carefully and even disconnected the display from one, cleaning the contacts and connector with IPA before reassembling. No joy. I can't see an obvious fault but I suspect there is a floating CMOS input on the second board.

Have I been extraordinarily unlucky or is Waveshare quality control generally suspect?
Peter Hinch

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Re: Waveshare hardware quality: any experience?

Post by scruss » Fri Jan 15, 2021 4:20 am

The WaveShare hardware that I have - some Raspberry Pi display/control hardware - is rather nice. The finish is good, and the soldering tidy. There is, however, a lot of knock-off equipment that carries their name - you'll see it sold at surprisingly low prices. WaveShare have been doing EPDs for a long time, so I'd be surprised if the design was bad. EPD QC can be variable: even quality suppliers like Pimoroni have sourced the wrong displays sometimes.

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Re: Hologram sticker

Post by pythoncoder » Fri Jan 15, 2021 8:35 am

scruss wrote:
Fri Jan 15, 2021 4:20 am
The WaveShare hardware that I have - some Raspberry Pi display/control hardware - is rather nice. The finish is good, and the soldering tidy...
Thanks for that. I can't fault the appearance of either board: I inspected them carefully and can't fault the apparent manufacturing quality. But that doesn't prove they are genuine. Knock-offs are a complete PITA.

They both have a hologram sticker "QC 07" but I guess these can be bought anywhere in China. Do genuine boards have a Waveshare hologram?
Peter Hinch

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