3.1 Interconnection between SAM L21 and AT86RF212B within ATSAMR30E18A SiP

This section describes the interconnection between SAM L21 and AT86RF212B. The interface comprises a client SPI and additional control signals. This interface is a host SPI interface in SAM L21 as shown in the following figure.

Figure 3-2. Interconnection between SAM L21 and AT86RF212B

The SPI is used for register, Frame Buffer, SRAM and AES access. The additional control signals are connected to the GPIO/IRQ interface of the microcontroller. The following table introduces the radio transceiver I/O signals and their functionality.

Table 3-1. Microcontroller Interface Signal Description
Signal Description
/SEL SPI select signal, active-low
MOSI SPI data (host output client input) signal
MISO SPI data (host input client output) signal
SCLK SPI clock signal
CLKM

Optional, clock output, usable as:

  • Microcontroller clock source and/or MAC timer reference
  • High precision timing reference
IRQ

Interrupt request signal, further used as:

  • Frame Buffer Empty indicator
SLP_TR

Multi-purpose control signal (functionality is state dependent):

  • Sleep/Wake up: enable/disable SLEEP state
  • TX start: BUSY_TX_(ARET) state
  • Disable/enable CLKM
/RST AT86RF212B Reset signal; active-low
DIG2

Optional:

  • IRQ_2 (RX_START) for RX Frame Time Stamping