Doc. No:
GR716-DEV-QSG
Issue:
0
Rev.:
2
Date:
2019-05-02
Page:
20 of 31
Status:
Draft
3.7
Clocking
The default configuration of the GR-CPCI-GR716-DEV board is to use the external 25 MHz crystal
oscillator Y1 (XTAL-DIL8_PCB) mounted on the GR716-BOARD as system and SpaceWire clock.
The GR716 device is designed to work with any crystal as long as the operating mode is of type
"Fundamental tone" and the frequency is in the range 4 MHz to 25 MHz. If SpaceWire is selected
as remote boot option design then external crystal oscillator frequency must be 5 MHz, 10 MHz, 20
MHz or 25 MHz.
The internal frequencies for ADC, DAC, MIL-1553, PackerWire, PWM, SPI4S, SpaceWire and
system depend upon the crystal oscillator frequency and on the internal clock logic and PLL
configuration. External system and SpaceWire clock source is selected with JP10 and JP11. If
SpaceWire is selected as remote boot option PLL should be configured via SPDT DIP switch S1
position 4 and 5.
Table 3
GR-CPCI-GR716-DEV clock configuration
Osclllitaor
Frequency
Mounted
Comment
X2
Upto 50 MHz
No
No need to mount if clock is no used on GR716-
BOARD (Default configuration)
X3
Upto 100 MHz *
No
No need to mount if clock is no used on GR716-
BOARD (Default configuration)
X4
Upto 200 MHz
No
No need to mount if clock is no used on GR716-
BOARD (Default configuration)
*
When SpaceWire is selected as remote boot option design then external crystal oscillator
frequency must be 5 MHz, 10 MHz, 20 MHz or 25 MHz.
© Cobham Gaisler AB
Default configuration
Default configuration is to clock distributed from the GR716-BOARD
