8mm Film Scanner ... my build

Machine Design
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@Manuel_Angel
For the motor control it has already been mentioned that the excellent pigpio library is no longer available on the PI5. But reading more in detail the pigpio documentation I see that it is possible to remote network control the pigpiod daemon. So it would be easily possible to continue using for the motor a RP3 or RPI4 running pigpiod. Maybe easier than using a pico or an arduino and no change in your software ?

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Hi @dgalland,

I hadn’t thought of this possibility.

@PM490 suggested the option of using a Pico microcontroller, which I personally didn’t know about either.

Although it takes a bit of time to get to grips with how a new microcontroller works, in this particular case, using MicroPython, you can get very good results in a short time.

The designers of the Pico microcontroller had the brilliant idea of ​​including programmable peripherals called state machines in the microcontroller itself. These state machines, once programmed, operate with their own clock, independently of the CPU, so that the timing of the motor control pulses is very precise.

RPi5-Pico communication is done relatively easily using a USB port on the RPi5 that is bridged to a UART on the Pico, using a Raspberry Pi Debug Probe and the Python serial module.

Using the Pico microcontroller also has the advantage of immunizing the system against future changes in the RPi hardware.

Here is a picture of my RPi5, with a prototyping board incorporating a Pico microcontroller and the Raspberry Pi Debug Probe.

IMG_20240207_191502
IMG_20240207_1915021920×1436 214 KB

3 Likes
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Thanks @Manuel_Angel I’ve used it now for several months and really like the performance (FPS) improvement of this design. For others that have missed my earlier post on it you will find it here https://forums.kinograph.cc/t/9-5-mm-scanner/2629 (June 3rd)

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Hi @Moevi.nl,

Thank you for your encouraging words.
I am glad that you are finding this version of the software useful.

Although I finished developing this version several months ago, I have not yet released it for general use, I have only sent it privately, as in your case, to users who have requested it.
The reason is that I find the software installation on the Pico microcontroller somewhat complicated and I want to make a detailed manual.

To make the software installation on the RPi5 easier, I am trying to make a .deb package or package it in an .AppImage file.

Kind regards

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I tried and it works without problem. As simple as this:

pi = pigpio.pi(‘192.168.1.152’)

So it is possible to recycle an old PI3 or PI4 to control the motor via the network from a PI5 with the Pigpio library with all its interesting possibilities.

3 Likes
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Hi @dgalland,

This is indeed an ingenious solution, instead of connecting to the pigpiod daemon running on the localhost, we connect to a daemon running on another RPi.

We also take advantage of an old RPi that we have forgotten in a drawer.

Thanks for sharing.

1 Like