Instructions to use MicroPython and font-to-py on a Pico powered Waveshare e-paper

[CoenTempelaars]

I have written a small instructable how to use the Writer class from micropython-font-to-py on a Pico powered 3.7 inch Waveshare e-paper, rotate the display 90 degrees and center the text horizontally and vertically.

https://www.instructables.com/Waveshare-E-paper-Display-With-Raspberry-Pi-Pico-M

[jimmo]

That's really cool! A 2.7" one of these literally arrived in the mail today, so keen to give this a go.

[peterhinch]

That is great!

You've actually done almost all of the work necessary to run nano-gui if you want to do more than display text. This will let you draw various controls, plot graphs and suchlike as per this demo:

[peterhinch]

Looking at your display driver I'm puzzled at the way you do rotation. Your approach allocates a 16,800 byte buffer every time you execute show. This runs the risk of an allocation failure after a period of running. One option is to allocate the buffer in __init__. But it seems to me that the buffer could be eliminated, with the rotation being done here as the data is output.

You've done a great job trimming Waveshare's wordy code, but there is scope for a further haircut. To give one example the .digital_write method doesn't do much and its calls could be treated thus:

self.digital_write(self.reset_pin, 1)

could be reduced to

self.reset_pin(1)

[CoenTempelaars]

Thanks for the feedback!

I'm going to start tinkering with nano-gui once I'm done with printing text in pretty fonts.

I like the idea of applying the rotation "on the fly" without the need for a separate buffer. I'm going to look into that, but that will definitely require some puzzling. If I fail to rotate the buffer "on the fly" then I'll change the code to allocate the extra buffer in __init__

I was not aware that Pins are callable in the way you describe. I'm going to remove the .digital_read and .digital_write methods once I figure out how to do that properly.

[peterhinch]

As a general comment I have just started porting the driver for the Waveshare 4.2 inch ePaper display. I spotted bugs in the first few minutes of looking at the Waveshare driver. Further, they evidently have no grasp of optimising MicroPython code. The more I look at their code, the less I like it. Perhaps someone can explain what can possibly be the point of

temp3 |= 0x00

because their driver is littered with similar...