The device has a set of internal registers
that can be accessed by the serial interface formed by the SEN
(serial interface enable), SCLK (serial interface clock) and SDIO (serial interface data
input/output) pins. Serially shifting bits into the device is enabled when
SEN is low. Serial data input are latched at every SCLK rising
edge when SEN is active (low). The serial data are loaded into the
register at every 16th SCLK rising edge when SEN is low. When the
word length exceeds a multiple of 16bits, the excess bits are ignored. Data can be
loaded in multiples of 16-bit words within a single active SEN
pulse. The interface can function with SCLK frequencies from 20MHz down to low speeds
(of a few hertz) and also with a non-50% SCLK duty cycle.