SPI communications
The XBee 3 802.15.4 RF Module supports SPI communications in slave mode. Slave mode receives the clock signal and data from the master and returns data to the master. The following table shows the signals that the SPI port uses on the device.
Refer to the XBee 3 Hardware Reference Guide for the pinout of your device.
| Signal | Direction | Function |
|---|---|---|
| SPI_MOSI (Master Out, Slave In) | Input | Inputs serial data from the master |
|
SPI_MISO (Master In, Slave Out) |
Output | Outputs serial data to the master |
|
SPI_SCLK (Serial Clock) |
Input | Clocks data transfers on MOSI and MISO |
|
SPI_SSEL (Slave Select) |
Input | Enables serial communication with the slave |
|
SPI_ATTN (Attention) |
Output |
Alerts the master that slave has data queued to send. The XBee 3 802.15.4 RF Module asserts this pin as soon as data is available to send to the SPI master and it remains asserted until the SPI master has clocked out all available data. |
In this mode:
- SPI clock rates up to 5 MHz (burst) are possible.
- Data transmission format is most significant bit (MSB) first; bit 7 is the first bit of a byte sent over the interface.
- Frame Format mode 0 is used. This means CPOL= 0 (idle clock is low) and CPHA = 0 (data is sampled on the clock’s leading edge).
- The SPI port only supports API Mode (AP = 1).
The following diagram shows frame format mode 0 for SPI communications.
SPI mode is chip to chip communication. We do not supply a SPI communication interface on the XBee development evaluation boards included in the development kit.
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