10.3 SPI Client Interface
The ATWILC3000-MR110xA module provides a Serial Peripheral Interface (SPI) that operates as an SPI Client. The SPI Client interface can be used for control and for serial I/O of IEEE 802.11 data. The SPI client pins are mapped as shown in the following table. The RXD pin is the same as Host Output, Client Input (MOSI) and the TXD pin is the same as Host Input, Client Output (MISO). The SPI Client is a full-duplex, client-synchronous serial interface that is available immediately following reset when pin 2 (SDIO_SPI_CFG) is tied to VDDIO.
| Pin # | SPI Function |
|---|---|
| 2 | CFG: Must be connected to VDDIO |
| 25 | SSN: Active Low Client Select |
| 23 | SCK: Serial Clock |
| 26 | RXD: Serial Data Receive (MOSI) |
| 24 | TXD: Serial Data Transmit (MISO) |
When the SPI is not selected (i.e., when the SSN is high), the SPI interface will not interfere with the data transfers between the serial host and the other serial client devices. When the serial client is not selected, its transmitted data output is buffered, resulting in a high impedance drive onto the serial host receive line.
The SPI Client interface responds to a protocol that allows an external Host to read or write any register in the chip and initiate DMA data transfers.