Closed bobemoe closed 2 months ago
Another possibility here would be, when connecting to an OBD port which has 2 ground pins, signal and chassis: The signal ground would connect to the middle GND pin along with the CAN hi/low lines, and the chassis ground would connect to the power GND along with the supply voltage line? I guess then the shield would connect to chassis ground.
Really if one of the designers of this board, or someone experienced in this, could shed some light on the intention of these middle GND pins that would be really helpful. Thanks.
Another possibility here would be, when connecting to an OBD port which has 2 ground pins, signal and chassis: The signal ground would connect to the middle GND pin along with the CAN hi/low lines, and the chassis ground would connect to the power GND along with the supply voltage line? I guess then the shield would connect to chassis ground.
Really if one of the designers of this board, or someone experienced in this, could shed some light on the intention of these middle GND pins that would be really helpful. Thanks.
AGND is used for the anti-static shielded ground interface of the CAN bus. DGND is used for the anti-static shielded ground interface of the RS485. The function of the two GNDs is to prevent static electricity and protect the circuit board. @bobemoe
The middle pins of the CAN and RS485 bus connectors are labelled AGND and DGND respectively on the schematic and are not connected directly to GND. It appears they connect to GND through a RC filter of some sort and are also connected to the transient voltage suppression components respectively for each bus.
What is the expected use of this pin. I cant work out if: