ALDL is an old GM protocol, used since the early 90’s through to about 2004ish. It was implemented on millions of vehicles, and is possibly the only single missing protocol that the macchina does not have implemented natively.
This projects purpose is to add in this missing protocol to the M2, with a very simple (And cheap!) hardware, and a library which should suit most vehicle applications.
Here is a link to the current github repo
Tested and working for 5v ALDL circuits at 8192 baud on pin9 of the standardized OBD2 (J1962) connector.
Next to add into the repo/thread is the hardware diagram + parts list which is basically a couple PNP transistors and resistor.