Bianca, I do not yet have the DMM Shield in hand, but looking at the documentation shows that it is using Arduino I/O Pins 11,12,13 for SPI. The Arduino Mega/Due do not have SPI on those pins, they only have SPI accessible on the ICSP header and the Mega additionally has it broken out on the I/O header at the end of the board. The DMM Shield does not connect to either the ICSP or the I/O Header at the end of the Mega/Due. How are you suggesting that we connect SPI to the DMM Shield? My only thought is to Set the Mega pins 11,12,13 as Inputs and then to jump the SPI pins on the Mega/Due to 11,12,13. Please let me know if this is the intended implementation or if there is some other method that you are claiming Mega/Due compatibility as I'm designing a Mega shield which the DMM Shield will connect to and I will need to include that update in my design if that is the intended method of connecting SPI.
On another note - I have two requests:
It is not clear in your documentation what the pinout is due to the additional headers and how they are described as 'top row' and 'bottom row' - is there a way you could add a visual pinout guide similar to the images you get when you search for 'arduino pinout' and just mark out the pins that are connected? I believe I understand after looking at the schematic, but it would be helpful to others as well.
It would be tremendously helpful if a mechanical drawing (or better yet, a 3d model) was available of this board. This would make it much easier for customers to determine mechanical constraints when working with this product.
Thanks, I look forward to getting several of these in hand and using them to automate some of our production testing!