When working with the CH9121 Module, you can use either the PicoConn or RJConn daughterboards with GigaBlox Nano. In both cases, connect one of the GigaBlox Nano ports directly to the RJ-45 port on the CH9121 module and the connection will come up.
You can connect GigaBlox Nano directly to the pins of the CH9121 chip without using transformers in between. This is beneficial because it saves space and cost on your board. To do this, you must remember the following points.
GigaBlox Nano (without the daughterboard) contains capacitors on the differential ethernet lines so you do not need to add anything between the connection (the capacitive coupling is included on GigaBlox Nano.
The maximum length of the copper traces between GigaBlox Nano and the CH9121 chip must not exceed 3 meters (this is unlikely to be an issue on a PCB).
The connection table below shows the correct pin mapping between GigaBlox Nano and the CH9121 chip.
| CH9121 pin name | CH9121 pin number | GigaBlox Nano Connection Name | GigaBlox Nano Pin example for Port 0 |
|---|---|---|---|
| TXP | 7 | Pn_A_P | 35 |
| TXN | 8 | Pn_A_N | 33 |
| RXP | 4 | Pn_B_P | 31 |
| TXN | 5 | Pn_B_N | 29 |
Where “n” is the GigaBlox Nano port.
CH9121 pinout
GigaBlox Nano pinout