Does any one have experience using L6474 chip from STmicro?
It seems like a powerful chip and ST provide a Uno pin-compatible breakout board at a very affordable price. However, it looks like a bit of nightmare to drive more than one board ( chip ) from a single SPI interface.
Someone ( of unknown merit/competence ) has been good enough to provide a library and some examples. Looks thorough on the face of it and I've tested the one motor example. https://github.com/MotorDriver/L6474
It seems that there is provision to "daisy-chain" several chips feeding MISO ( slave output ) of one chip into MOSI on the next, with the Uno just feeding to the first chip's MOSI.
Now I'm presumably missing a trick somewhere but I can't see how this works and although I do have some hardware to test, I don't have a logic analyser to watch and capture every pulse.
Can someone explain?
For example there is a GetStatus command that sends one byte and receives two in response.
Say I have three chips stacked ( they piggyback each other ) and connected in daisy-chain config , how is it possible for this command to be sent exclusively to, say, the second board and for that board to get the response back to Uno via the third one in the chain?
There some SMC null resistors to use as links which allow separate step, dir and CS lines for each chip. They have to share MOSI, MISO, SCK but these can also be moved to daisy-chain the boards rather than have all fed in parallel from the Arduino pins 12,13,14. In daisychain all CS are connected together to Uno.