The AFEx81H1 are controlled over a versatile four-wire serial interface (SDIN, SDO, SCLK, and CS). The interface operates at clock rates of up to 12.5 MHz and is compatible with SPI, QSPI, Microwire, and digital signal processing (DSP) standards. The SPI communication command consists of a read or write address, a data word, and an optional CRC byte.

The SPI can access all register addresses except for the UBM register. Read-only and read-write capability is defined by register (see Table 7-13). The SPI supports both SPI Mode 1 (CPOL = 0, CPHA = 1) and SPI Mode 2 (CPOL = 1, CPHA = 0). The default SCLK value is low for SPI Mode 1 and high for SPI Mode 2. See Section 6.7 for timing diagrams in each mode. The serial clock, SCLK, can be continuous or gated.