STLC4420A
4
Serial host interface
Serial host interface
4.1
Host pins
The Serial Host Interface consists of the following pins:
● SPI_CLK: serial host clock input, 0 to 48 MHz.
● SPI_DIN: serial host data input, sampled on active edge of SPI_CLK.
● SPI_DOUT: serial host data output, driven when asserted low and floating when de-
asserted. SPI_DOUT is driven on inactive edge of SPI_CLK.
● SPI_CSX: serial host chip select, active low chip select.
● HOST_IRQ: serial host interrupt, active high interrupt to Host.
The serial host interface has 12 modes of operation controlled by 4 variables. The default
4-Wire mode may be changed by a SPI host write to the device status/ control register. If the
host requires a different SPI mode for normal operation, the host may need to toggle the
necessary SPI pins using GPIO-style interfacing to perform a 4-Wire write sequence to
change the mode.
The default 4-Wire single word write is show below in Figure 4.
Figure 4. 4-Wire mode single word write
The default 4-Wire single word read is shown below in Figure 5.
Figure 5. 4-Wire mode single word read
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