FTDI LibFT4222 - Figure 3.5 SPI Master Transfer Request; Figure 3.6 an Example of the SPI Slave Responding with ACK; Figure 3.7 an Example of When the SPI Master Doesnt Receive ACK

Application Note
AN_329 User Guide For LibFT4222
Version 1.5
Document Reference No.: FT_001060 Clearance No.: FTDI#406
35
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Figure 3.5 SPI Master Transfer Request
Here is an example of an ACK packet. The SN field of the ACK packet identifies which request it
corresponds to. An ACK packet has no data therefore the Size field should be 0.
Figure 3.6 An example of the SPI slave responding with ACK
If the SPI master does not receive the ACK response from the slave, it should send its request
again.
Figure 3.7 An example of when the SPI master doesn’t receive ACK
When the FT4222H SPI slave wants to send data to the master, which may be requested by the
master, it just sends a transfer request in the same protocol format as shown in figure 3.4.
In this case, it is not necessary to append any header while API FT4222_SPISlave_Write is called.