Datasheet

3-6
3.2.2 SRC4194 Software Mode Configuration Via The Host Port
In Software mode, the SRC4194 relies upon an external host device to pro-
gram the internal control registers via the four-wire SPI port. The SPI port is
accessed using the Host Port header, connector J1. The header is buffered
by U2, an octal buffer IC with tri-state outputs. The buffer outputs are enabled
only when the H/S
element of switch SW2 is set to the LO state. When H/S is
HI, the buffer outputs are set to a high-impedance state.
The Host Port header provides a convenient interface point for connection to
an external host device, such as a microprocessor, a digital signal controller/
processor, or a digital input/output card installed in a PC.
Refer to the SRC4194 datasheet for a description of the SPI port protocol and
control register definitions.