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Problems getting EVAL6470PD starter kit to work

Question asked by matsumoto.dave on Jun 26, 2013
I'm trying to evaluate the L6470 with the EVAL6470 starter kit, and I can't make sense of the problems that I am experiencing.  For quick prototyping, I'm pairing the kit with my mbed LPC1768 and just want to read the status register to make sure that basic comms is working as expected.

I see two ways to query status:
1.  Use the GetParam command and pass STATUS for param
2.  Use the GetStatus command

My first question is, are these equivalent?  I would expect that I can query for the status either way, and I should get the same result back, with the exception of faults getting reset when GetStatus is used.

I believe I have the wiring done correctly:
  • MISO -> MISO
  • MOSI -> MOSI
  • SCLK -> SCLK
  • CS -> CS
  • STBY/RST -> 3.3V
  • GND -> GND
  • everything else left floating
Any time I use the GetParam command, the value I receive from the L6470 makes little sense.  For example, in this case I want to read the status register, which is 0x19.  So I sent 0x39 followed by two NOP commands, [0x39, 0x00, 0x00].  The response to the command is [0x00, 0x3D, 0x80].

When I send GetStatus, [0xD0, 0x00, 0x00], I get back [0x00, 0x78, 0x00].

Not only are these two values different, but they also don't make sense.  At least in the latter case, I don't believe I have any thermal issues because the motor isn't even enabled.

Can anyone suggest reasonable next steps for debugging this problem?  I'm going to hook up a logic analyzer later to verify the SPI comms, but other than that, are there other things I can try?