Upgrading Clearfog Pro to support CN9130 SOM

This guide is meant to explain how to upgrade the the ClearFog Pro to support both CN9130 SOM and A388 SOM.

25MHz reference clocks for Ethernet Switch and PHY

Note: Clearfog Pro revision 2.2.9 and later already include these changes.

Dis-/Assemble the components from table below:

#	RefDes	Action	Comments
1	R140	Remove	resistor 220Ω
2	R141	Remove	resistor 499Ω
3	C52, C55	Add	capacitor 22pF
4	Y1	Add	crystal 25MHz 3.2mm x 2.5mm SMT
5	R138	Remove	resistor 220Ω
6	R139	Remove	resistor 499Ω
7	C154, C158	Add	capacitor 22pF
8	Y2	Add	crystal 25MHz 3.2mm x 2.5mm SMT

The components locations are marked green / red in the pictures below:

Components side

cfpro_a38x_cn9130_phy_clock.png

Print Side

cfpro_a38x_cn9130_dsaswitch_clock.png

Impact

CN9130 SoM does not provide a 25MHz reference clock output, The changes outlined disconnect the SoM reference clock signal and replace it with crystals for both ethernet switch and port 6 phy.

SFP Rate-Select (RS0/RS1)

Note: Clearfog Pro revision 2.2.12 and later already include these changes.

Dis-/Assemble the components from table below:

#	RefDes	Action	Comments
1	R102, R103	Remove	resistor 0Ω
2	R95, R96	Add	resistor 1kΩ

The components locations are marked red in the picture below:

cfpro_a38x_cn9130_sfp.png

Impact

R95/R96 enable high-speed mode (10Gbps) for TX and RX on SFP modules. Without this change CN9130 SoM SFP port will be limited to sgmii (2.5Gbps and lower) speeds even though the cpu side supports up to 10Gbps.