GS9092A_10 Datasheet, PDF (53/63 Pages) Gennum Corporation – GenLINX III 270Mb/s Serializer for SDI and DVB-ASI

3.13 GSPI Host Interface
The GSPI, or Gennum Serial Peripheral Interface, is a 4-wire interface provided to allow
the host to enable additional features of the GS9092A and/or to provide additional status
information through configuration registers in the device.
The GSPI comprises a serial data input signal SDIN, serial data output signal SDOUT, an
active low chip select CS, and a burst clock SCLK.
Because these pins are shared with the JTAG interface port, an additional control signal
pin JTAG/HOST is provided. When JTAG/HOST is LOW, the GSPI interface is enabled.
When operating in GSPI mode, the SCLK, SDIN, and CS signals are provided by the
application interface. The SDOUT pin is a non-clocked loop-through of SDIN and may
be connected to the SDIN of another device, allowing multiple devices to be connected
to the GSPI chain. The interface is illustrated in Figure 3-12.
Application Host
SCLK
CS1
SDOUT
GS9092A
SCLK
CS
SDIN
SDOUT
CS2
SDIN
GS9092A
SCLK
CS
SDIN
SDOUT
Figure 3-12: GSPI Application Interface Connection
All read or write access to the GS9092A is initiated and terminated by the host processor.
Each access always begins with a 16-bit command word on SDIN indicating the address
of the register of interest. This is followed by a 16-bit data word on SDIN in write mode,
or a 16-bit data word on SDOUT in read mode.
NOTE: All unused GSPI input pins (CS, SDIN, SCLK) should be pulled up to VCC_IO.
GS9092A GenLINX® III 270Mb/s Serializer for SDI and
DVB-ASI
Data Sheet
34715 - 4
May 2010
53 of 63