STLC4420A datasheet(21/40 Pages) STMICROELECTRONICS

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STLC4420A

Serial host interface

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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.

The default 4-Wire single word read is shown below in Figure 5.

Figure 4.

4-Wire mode single word write

Figure 5.

4-Wire mode single word read

STLC4420A Datasheet(PDF) 21 Page - STMicroelectronics