GS4910B GENNUM [Gennum Corporation], GS4910B Datasheet - Page 76

• Manufacturer Part Number: GS4910B
• Description: HD/SD/Graphics Clock and Timing Generator with GENLOCK
• Manufacturer: GENNUM [Gennum Corporation]

3.12 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 GS4911B/GS4910B and/or to
provide additional status information through configuration registers in the device.
The GSPI comprises a serial data input signal, SDIN, a serial data output signal,
SDOUT, an active low chip select, CS, and a burst clock, SCLK. The burst clock
must have a duty cycle between 40% and 60%.
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 pin of another device, allowing multiple devices
to be connected to the GSPI chain. The interface is illustrated in
Figure 3-14: GSPI Application Interface Connection
All read or write access to the GS4911B/GS4910B 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.
36655 - 2
Application Host
April 2006
SDOUT
SCLK
SDIN
CS2
CS1
GS4911B/GS4910B Data Sheet
SDOUT
SDOUT
SDIN
CS
SDIN
SCLK
CS
SCLK
GS4911B/GS4910B
GS4911B/GS4910B
Figure
3-14.
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