GS6150 Datasheet, PDF (29/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

4.11 GSPI Host Interface
The GS6150 is controlled via the Gennum Serial Peripheral Interface (GSPI).
The GSPI host interface is comprised of a serial data input signal (SDIN pin), serial data
output signal (SDOUT pin), an active-low chip select (CS pin) and a burst clock (SCLK
pin).
The GS6150 is a slave device, therefore the SCLK, SDIN and CS signals must be sourced
by the application host processor.
All read and write access to the device is initiated and terminated by the application
host processor.
It is strongly recommended to connect the GSPI pins of the GS6150 to a host/system
processor/controller or FPGA to facilitate optimization of the device to meet specific
application requirements. Modification of many device settings is only facilitated
through the GSPI of the GS6150, and is not available on external pins.
4.11.1 CS Pin
The Chip Select pin (CS) is an active-low signal provided by the host processor to the
GS6150.
The high-to-low transition of this pin marks the start of serial communication to the
GS6150.
The low-to-high transition of this pin marks the end of serial communication to the
GS6150.
There is an option for each device to use a separate unique Chip Select signal from the
host processor or for up to 32 devices to be connected to a single Chip Select when
making use of the Unit Address feature.
Only those devices whose Unit Address matches the UNIT ADDRESS in the GSPI
Command Word will respond to communication from the host processor (unless the
B’CAST ALL bit in the GSPI Command Word is set to 1).
4.11.2 SDIN Pin
The SDIN pin is the GSPI serial data input pin of the GS6150.
The 16-bit Command and Data Words from the host processor or from the SDOUT pin
of other devices are shifted into the device on the rising edge of SCLK when the CS pin
is low.
4.11.3 SDOUT Pin
The SDOUT pin is the GSPI serial data output of the GS6150.
All data transfers out of the GS6150 to the host processor or to the SDIN pin of other
connected devices occur from this pin.
By default at power up or after system reset, the SDOUT pin provides a non-clocked path
directly from the SDIN pin, regardless of the CS pin state, except during the GSPI Data
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
29 of 64
Proprietary & Confidential