3.2.6.6.2 SPI Bus Distribution
The SAMA7G54-EK features two dedicated SPIs to access the on-board devices.
The Serial Peripheral Interface (SPI) circuit is a synchronous serial data link that provides communication with external devices in Host or Client mode. It also enables communication between processors if an external processor is connected to the system.
The SPI system consists of two data lines and two control lines:
- Host Out Client In (MOSI)—This data line supplies the output data from the host shifted into the input(s) of the client(s).
- Host In Client Out (MISO)—This data line supplies the output data from a client to the input of the host. There may be no more than one client transmitting data during any particular transfer.
- Serial Clock (SPCK)—This control line is driven by the host and regulates the flow of the data bits. The host can transmit data at a variety of baud rates; there is one SPCK pulse for each bit that is transmitted.
- Client Select (NSS)—This control line allows clients to be turned on and off by hardware.
The first interface is used to access the following devices:
- Any device placed on the mikroBUS 1 connector. Flexcom11 in SPI mode is used to address this interface. Chip Select 0 is used to select the device available in this interface.
- Any device placed on the mikroBUS 2 connector. Flexcom11 in SPI mode is used to address this interface. Chip Select 1 is used to select the device available in this interface.
| PIO | MPU Net Name | Device Net Name | Function |
|---|---|---|---|
| PB3 | FLEXCOM11_IO0_PB3 | MIKROBUS1_MOSI_PB3 | SPI MOSI line mikroBUS 1 |
| MIKROBUS2_MOSI_PB3 | SPI MOSI line mikroBUS 2 | ||
| PB4 | FLEXCOM11_IO1_PB4 | MIKROBUS1_MISO_PB4 | SPI MISO line mikroBUS 1 |
| MIKROBUS2_MISO_PB4 | SPI MISO line mikroBUS 2 | ||
| PB5 | FLEXCOM11_IO2_PB5 | MIKROBUS1_SCK_PB5 | SPI clock line mikroBUS 1 |
| MIKROBUS2_SCK_PB5 | SPI clock line mikroBUS 2 | ||
| PB6 | MIKROBUS1_CS_PB6 | MIKROBUS1_CS_PB6 | SPI Chip Select 0 mikroBUS 1 |
| PB7 | MIKROBUS2_CS_PB7 | MIKROBUS2_CS_PB7 | SPI Chip Select 1 mikroBUS 2 |
The second interface is used to access the following devices either in SPI mode or in USART mode:
- Any device placed on the RPi 40-pin connector. Flexcom0 in SPI mode is used to address this interface. Chip Select 0 and Chip Select 1 are used to select the device(s) available in this interface.
- WILC3000 USART interface. Flexcom0 is used in USART mode.
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Note: Only IO0, IO1, IO3 and IO4 are shared between these two interfaces. IO2 (clock) is reserved to SPI mode only.
| PIO | MPU Net Name | Device Net Name | Function |
|---|---|---|---|
| PE3 | PE3 | EXT40_SPI1_MOSI_PE3 | SPI MOSI line RPi 40-pin connector |
| BT_RX_FLEXCOM0_IO0_PE3 | WILC3000 USART RX line | ||
| PE4 | PE4 | EXT40_SPI1_MISO_PE4 | SPI MISO line RPi 40-pin connector |
| BT_TX_FLEXCOM0_IO1_PE4 | WILC3000 USART TX line | ||
| PE6 | PE6 | EXT40_SPI1_CE0_PE6 | SPI Chip Select 0 RPi 40-pin connector |
| BT_RTS_FLEXCOM0_IO3_PE6 | WILC3000 USART RTS line | ||
| PE7 | PE7 | EXT40_SPI1_CE1_PE7 | SPI Chip Select 1 RPi 40-pin connector |
| BT_CTS_FLEXCOM0_IO4_PE7 | WILC3000 USART CTS line | ||
| PE5 | EXT40_SPI1_SCLK_PE5 | EXT40_SPI1_SCLK_PE5 | SPI clock line RPi 40-pin connector |