So I purchased a cheap Double-7-Segment display piece (specifically this one: https://www.amazon.com/dp/B01D0WSCJA)
To do some tinkering with. I've messed around with it manually to make sure it works and it does. However from reading the datasheet I can't quite tell if the 7219 supports SPI. The datasheet im using is: https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf
It states that the 7221 supports SPI but doesn't mention anything for the 7219. So when dealing with this with a normal MCU...do we just bitbang it specifically trying to match the timing diagram?
If that's true (and this is one I ran into when doing it manually with switches/buttons for testing) I get confused on the last timing portion. Specifically when CS/LOAD goes high and then low the last time. Do we pull CS/LOAD high on the last Data bit CLK latch? or does it have to go high RIGHT as the CLK is falling on the last data bit?
And we just need to make sure the LOAD stays high for a sufficient time before pulling it back down? (The last data bit portion always screwed me up). Im having a hard time telling how to handle that in code (Since I screwed up doing it manually, which I tend to try out to learn the datasheet first). I just can't tell if it matters when LOAD goes high at the very end if that needs to be when CLK has latched the last data bit or it needs to start going high before then. The data is latching on the rising edge correct? (of CLK)
One thing I learned when testing this was that it has to be put in Shutdown Mode-Normal operation before doing anything (Which had me stumped for awhile). Because I thought it would be accepting data when it was first started up. Is there anything else im missing on "startup" mode?