The PCB for the Arduino Mega 2560 finally got populated and somewhat tested. The layout is not perfect and the result isn't quite fit for the promotion poster, but probably good enough for testing and usage. This project is just to make digital logic I.C.s testing easy, not to win beauty contests.
Some issues found with construction and testing:
- the LED resistor value of 330 ohm is way to low for the Arduino pins. It is changed to 3k3 ohm.
- the resistor arrays were hard to find and weren't the designed size, so some extra resistors were needed to fill the missing positions. It would look better if all positions were discrete resistors.
- The MOSFETs ordered had a different package than the PCB design.
The next stage is:
- to test the board,
- add more and larger I.C.s to the library,
- implement test algorithms for tri-state, open collector, ...
At one time I might upload an updated schema and PCB, but as long as the current design is fixable, I won't order and test it.
There are five pins were power can be applied, being the highest pin number for 14, 16, 20, 24 and 28 pin I.C.s. For different power pin schemes, the breadboard solution of the prototype could be used.