6.1.5 SPI Communication Procedure

Writing to an SPI client device from a specified location:

1. Configure the SPI interface:
   • Send SPI_Configure command through Endpoint 0x06, OUT with the following parameters:

     Parameter	Value	Description
     Command	0x20	Configure the SPI
     Clock speed	0x30 0x20 0x32 0x22 0x34 0x24 0x26	12 MHz clock speed 6 MHz clock speed 3 MHz clock speed 1.5 MHz clock speed 750 kHz clock speed 375 kHz clock speed 187.5 kHz clock speed
     SPI mode	0x44 0x45 0x46 0x47	SPI mode 0 SPI mode 1 SPI mode 2 SPI mode 3
     Chip-select and its active state	0x00 0x01 0x40 0x41 0x80 0x81 0xC0 0xC1	CS0 active low CS0 active high CS1 active low CS1 active high CS2 active low CS2 active high CS3 active low CS3 active high
     Delay between: Chip-select assertion and the first data byte Each data bytes The last data byte and chip-select de-assertion	0x0000 0x000A 0x0014 … 0x03E8 … 0x1388	0 μs 10 μs 20 μs ... 1 ms ... 5 ms

• Read the response through Endpoint 0x86 (IN). The response can be one of the following:

  • Response code	Status	Action
    0x20	Response to SPI Config	Continue reading
    0x20 0x60 0x64	The SPI interface is configured. Invalid parameters. The SPI module is busy.	Proceed to the write transaction. Retry with valid parameters. Wait and retry later.

• Send the SPI_Write command through Endpoint 0x06 (OUT) with the following parameters:

• Read the response from Endpoint 0x86 (IN). Possible initial responses are:

  Response code	Status	Action
  0x24	Response to SPI Write	Continue reading
  0x22 0x60 0x64	The SPI write transaction is initiated. Invalid parameters. The SPI module is busy.	Proceed to continue the write transaction. Retry with valid parameters. Wait and retry later.

• If the number of data bytes to write exceeds 60 bytes, send continuation packets through Endpoint 0x06 (OUT). Each continuation packet includes:

  Parameter	Value	Description
  Command	0x24	Write to the SPI client device is continued.
  Continuation flag	0xA0
  Data bytes	vWrDtPac	Data to write (up to 62 bytes)

• After each continuation packet, and after the write transaction is completed, read the response from Endpoint 0x86 (IN). The response can be one of the following:

  Response code	Status	Action
  0x24 NACK	Response to SPI Write. No response available yet.	Continue reading. Continue polling.
  0x22 0x68 0x20	The SPI write transaction is continued. The buffer is full. The SPI write transaction is successfully completed.	Proceed to continue the write transaction. Retry until the packet is accepted.

• Repeat sending the continuation packets through Endpoint 0x06 (OUT) and polling Endpoint 0x86 (IN) until all the required data bytes are written

Reading data from an SPI client device from a specified location: