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DRV8804: Serial interface protocol

Adam Lawrence
Prodigy 20 points
Part Number: DRV8804


Is there a document which defines the protocol with which this device reports and expects data? The closest thing to a reference I could find is the EVM firmware source code. The driver datasheet itself (SLVSAW4F) makes no mention of the bits/bytes needed to communicate with the device, nor does it contain a reference to this information in another document. It only describes the electrical/logical operation of the serial interface.

  • +1
    Prodigy 20 points

    Or, am I to assume that all this device can do is accept 4 bits to control the steps, and report back the status of those bits?

  • 0 in reply to Adam Lawrence
    TI__Mastermind 23451 points

    Hey Adam,

    Sorry this post got missed!

    Your comment is correct, it is simply a shift register inside the device that controls the outputs.  See Figure 6 below in 7.3.2 Serial Interface Operation.

    6.6 Timing Requirements gives a data timing diagram as well:

    From this E2E post,

    1. SDATIN signal controls the OUTx pin's output. SDATIN Data (expected OUTx high or low value.) is shifted into a temporary holding shift register (LATCH pin doesn't allow the data passing to OUTx) in the part using the SDATIN pin, one bit at each rising edge of the SCLK pin. For example: if they want OUT1 high, OUT2 low; OUT3 high; OUT4 low. They just send SDATIN low high low high signal.

    2. After SDATIN data is sent out, a rising edge on the LATCH pin latches the data from the temporary shift register into the output stage.

    Regards,

    Jacob