Times They Are A Changin'

General Discussions
1

The problem is we are asked/told to adjust our thinking about everything:

  • The Hardware is changing every two years or so
  • Hardware-OS interface philosophy changes every few years
  • The Operating Systems are advancing every year, (2 years for Long Term Support versions)
  • The Programming Languages introduce major changes every 5 to 10 years
  • System management environments and practices (build, configuration management, repositories): 3-5 years
  • Product APIs have to keep up with all the above changes
  • Domain environments are changing every year (ROS, TensorFlow, Keras, PyTorch, OpenCV)

In this particular case where the GoPiGo3 C++ API was much less packed with features than the Python API, it turned out to be easier to get “Hello World” and the GoPiGo3 motors to work on the Pi5.

I am not aware of the reason the GoPiGo3 Python API needs the pigpiod package or GPIO bit twiddling in the API.

For Reference This is the GoPiGo3 GPIO pin usage that I am aware of:

GoPiGo3 - Raspberry Pi Interface
 13v3: RPI+3v3
 2:5V: 5V supply
 3:GPIO2: SDA_3v3
 4:5V: 5V supply
 5:GPIO3: SCL_3v3
 8:GPIO14: RPI_TX
10:GPIO15: RPI_RX
12:GPIO18: RPI_RESET
15:GPIO22: RPI_Shutdown (button)
16:GPIO23: RPI_RUNNING
18:GPIO24: RPI_SWDIO
19:GPIO10: RPI_MOSI
21:GPIO9: RPI_MISO
22:GPIO25: RPI_SWDCLK
23:GPIO11:RPI_SCK
26:GPIO7: RPI_SS

For GPIO22/23 (“GoPiGo3 Power Management”) the Python package RPI.GPIO was used which is supported on the Pi4, but not on the Pi5. The new package gpiod was not well documented that I could find, but since the power management routine was only 6 lines, it was reasonably easy to port.

I didn’t feel I could port the entire GoPiGo3 Python API for a feature I didn’t know how it is used, and thus didn’t know how I would test the port. My method for porting to Bookworm was to remove anything that broke. I didn’t know how to remove stuff that breaks without knowing what it does.

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2

As I remember, this stuff was all supposed to be "backward compatible.  (i.e.  Anything written for the Pi version “x” would work on any previous version - with the possible exception of the Pi-1.)  What happened?  Why is the -5 so different?  I know there were architecture changes between the 3 and the 4, but at the user/programming level things were the same - with the architecture changes being reflected in the device tree overlay files (.dts) loaded at boot-time.  Once that was done, you were golden!  That is unless you were programming “bare metal”. :wink:

One solution might be to recompile a custom device tree overlay that puts things where the GoPiGo expects them, but - based on what I’ve seen - it’s gnarlier than a scrub pine forest on a windy plain.

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