GS9090 Data Sheet
PCLK
XYZ
(eav)
XYZ
(sav)
Y/Cr/Cb DATA OUT
3FF
000
000
3FF
000
000
H
V
F
Figure 3-14: H,V,F Timing In Low-latency Mode
3.14 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 GS9090 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 3-15.
Application Host
GS9090
SCLK
CS
SCLK
CS1
SDOUT
SDIN
SDOUT
GS9090
SCLK
CS2
CS
SDIN
SDOUT
SDIN
Figure 3-15: GSPI Application Interface Connection
All read or write access to the GS9090 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.
28201 - 1 July 2005
59 of 70
GENNUM [ GENNUM CORPORATION ]
