SPRUIS4E March 2022 – January 2024
In addition to the Primary clock, the SERDES reference clocks to the SoC is sourced from the Clock Generator (CDCI6214) on the Common processor board. All these clocks are 100 MHz with HCSL level for the SoC’s SERDES reference clock input. The programming of CDCI6214 chip is done through J721E SoC’s I2C0 port.
There are two CDCI6214 clock generators available to source the SERDES reference clocks to SoC. The CDCI1 (U22) is not connected to I2C0 port by default. The clocks from CDCI1 (U22) is derived using factory programmed configuration.
Only the CDCI2 (U17) is required I2C programming for the desired clock outs from each channel. A 25 MHz crystal is attached the each CDCI chip for its reference clock inputs.
Signal/Net Name | Probe Point | Clock Gen/CH | Description | Frequency |
---|---|---|---|---|
CLKGEN_SERDES1_REFCLK_P/N | R176/ R167 | CDCI1/Y1 | 100MHz HCSL Clock to SoC SERDES1 | 100 MHz |
CLKGEN_PCIE0_1L_REFCLK_P/N | R143/ R142 | CDCI1/Y2 | 100 MHz HCSL Clock to PCIe0 x1 L Socket | 100 MHz |
CLKGEN_SERDES0_REFCLK_P/N | R145/ R153 | CDCI1/Y3 | 100 MHz HCSL Clock to SoC SERDES0 | 100 MHz |
CLKGEN_PCIE0_2L_REFCLK_P/N | R168/ R177 | CDCI1/Y4 | 100 MHz HCSL Clock to PCIe0 x2 L Socket | 100 MHz |
CLKGEN_SERDES2_REFCLK_P/N | R158/ R157 | CDCI2/Y1 | 100 MHz HCSL Clock to SoC SERDES2 | 100 MHz |
CLKGEN_USB_REFCLK_P/N | R160/ R159 | CDCI2/Y2 | 100 MHz HCSL Clock to SoC USB | 100 MHz |
QSGMII_PHY_REFCLK_P/N | C108/ C109 | CDCI2/Y3 | 125 MHz LVDS Clock to Ethernet Expansion board | 125 MHz |
CLKGEN_PCIE2_2L_REFCLK_P/N | R123/ R124 | CDCI2/Y4 | 100 MHz HCSL Clock to PCIe M.2 Socket | 100 MHz |
The PCIe reference clocks to the PCIe x1, x2 and M.2 sockets are also derived from the CDCI clock generators.