– Copied from customer query –
I’m working on a PCB design that includes a GigaBlox Nano ethernet switch and a Raspberry Pi Compute Module 5 and I was wondering if you have any recommended circuit diagram for interfacing between the Raspberry Pi and the GigaBlox switch via ethernet. Both devices will be mounted on the same PCB and will only be around an inch apart. I thought this might be something that someone has done before so you might have some advice?
Thanks for reaching out.
We don’t have an example circuit for this, but in theory this should be very achievable.
The raspberry pi CM5 uses a BCM54210PE chip, which uses a voltage mode ethernet PHY. This means it can be interfaced directly with GigaBlox Nano without needing transformers.
To do this you would simply connect the CM5 pins to the appropriate GigaBlox Nano pins.
So you would do.
CM5 ↔ GigaBlox Nano
TRD0_P ↔ Pn_A_P
TRD0_N ↔ Pn_A_N
TRD1_P ↔ Pn_B_P
TRD1_N ↔ Pn_B_N
TRD2_P ↔ Pn_C_P
TRD2_N ↔ Pn_C_N
TRD3_P ↔ Pn_D_P
TRD3_N ↔ Pn_D_N
GND ↔ GND
Where n is the number of the port you choose to connect to on GigaBlox Nano.
You’d want to keep your traces short, and matched impedance of 100Ohm with matched intra-pair skew of less than 5mm.
Let me know if that makes sense.