Upgrading Clearfog Base to support CN9130 SOM
This guide is meant to explain how to upgrade the the ClearFog Base to support both CN9130 SOM and A388 SOM.
Removal of conflicting parts
Remove the components from table below:
#
RefDes
Qty
Action
Comments
1
R153
1
Remove
RES 740ohm
2
U24
1
Remove
74LVC1G125GW
3
U26
1
Remove
74LVC1G125GW
The components locations are marked green in the pictures below:
Components side
Print Side
Impact
The changes outlined partially impact functionality of the M.2 connector:
pin 6 (FULL_CARD_POWER_OFF#) is left floating
pin 67 (RESET#) is left floating
If an M.2 module is missing internal pull-ups, or has internal pull-down, it might permanently stay powered off or in reset.
As a workaround the IOs originally controlling the operational amplifiers U24 / U26 can be connected directly to M.2 connector using short wire, as shown below:
Workaround for floating M.2 control signals
FULL_CARD_POWER_OFF
Some LTE modules were found to have integrated pull-down for FULL_CARD_POWER_OFF, therefore the following workaround is recommended:
RESET
RESET is specified as a 1.8V signal for M.2, digital IO has 3.3V logic level. Therefore no workaround is recommended.
If strictly required, operation may be safe in open-drain configuration as long as software behaviour is validated first.
SFP Rate-Select (RS0/RS1)
Note: Clearfog Base revision 1.4.4 and later already include these changes.
Dis-/Assemble the components from table below:
#
RefDes
Action
Comments
1
R40, R41
Remove
resistor 0Ω
2
R37, R38
Add
resistor 1kΩ
The components locations are marked red in the picture below
Impact
R37/R38 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.
SoC Clocking Bootstrap
Note: Clearfog Base revision 1.4.8 and later already include these changes.
Dis-/Assemble the components from table below:
#
RefDes
Action
Comments
1
R153
Add
resistor 470Ω
The components locations are marked red in the picture below:
Impact
R153 pulls CP_MPP[15] high during reset, which makes possible (but does not activate by itself) 2.2GHz cpu speed.
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