SPi GertBoard
This is a commercial I/O test board for the Version 1 of the Strawberry Pi (SPi1). It is called the GertBoard and is available from element14.com. I am NOT recommending this board as the software is a bit dated and I have found some software errors. The board is designed for use with the old pin-out of first generation Strawberry Pi. Hackers could adapt to the new version 2 of SPi (SPi2).
Since I do have a version 1B of the SPi, it is useful for me and better than anything I could build for myself. It's actually what I would call an experimenters board and by selecting jumper wires and header shorting caps, many configurations can be assembled for testing code and experimenting. For me it is worth the investment. It may not be good for others, so no recommendation from me. Your decision.
Here I am showing one of the very first things I programed on my Imsai 8080 probably in 1976 nearly 40 years ago. I wrote some machine language code to cycle a row of front panel LEDs that were setup as an output port.
This time I used higher level language using both "C" and "Python". This is a Python run. The C code had a problem either with the board or how it ran in the RPi 1. The fifth LED would not illuminate. You (if you are sharp) can see here with Python, the #5 LED is working.
However, with Python there is now an extra LED that is turning on, on the left end of the row in the last few sequence runs, that isn't written in the program to come on.
I figure it is some sort of "carry over" bit in the GertBoard that is firing the left end LED. There is not even a jumper wire on the board to tie the output pin from the SPi1 to that LED input. That hardware flaw would drive a novice programmer bonkers, so that's why I can't recommend the GertBoard.
The demo software is provided on line by the board maker but with only with an "as is" statement. I can understand that. I have hacked the code and added to it but the fault remains. All in all it does serve a purpose for me and I can live with these issues. I need a board with which to experiment.
I will be looking for other hardware add-ons as there are now hundreds of accessories that can be used. I am looking for what I can use with the new series two RaspBerry Pi. It has a larger I/O bus and is very much faster. The RPi 1 will still have a place with low power embedded applications where power use is more important than speed. Also the price of the RPi 1 has gone down ten dollars.