On the interface page, we removed the XOR gate that was previously used for the external charging logic. This was handled by software in the previous revision so it is now removed to avoid confusion. We also decided to update the buffer circuits to powerboard and Precharge, so that they would now both use one PMOS to buffer a 5 V signal to each board. On each respective board now, that 5 V signal would get buffered, and in turn help reduce dependencies across the boards. We had to make sure to implement these changes to each of these boards during the same revision, or else we would not have been able to turn the car on or drive the motors.
On the Moduleboard interface schematic, we decided to remove the 0-ohm jumper that was previously used to start the 5 V logic line for the Moduleboard analog fault. Since we always needed this connected, it was one less part to manage and worry about on the working revision of the board. On the regulator page, we decided to change the 5 V regulator from the previous linear regulator to the standardized switching regulator circuit that was used on other boards. This is a push I made as both the manager and Librarian for parts standardization. We also removed the 2.5 V regulator since we did not use it anymore on Headnode.
The microcontroller page remained the same, but we did update the schematic block so that there was less text on it, which made it more readable.
The relay logic page removed the 2 0 Ohm resistor jumpers that were used to select between the relay and power switches that would be used to power 12 V to the battery pack relays. After we were able to receive and test the power switch part, we determined that they were more efficient and easier to implement, which is what we did on this revision. The circuit was created from the recommended parts and connections in the datasheet. We used to logic signal mentioned previously to turn them on, with a 5 V input. We used the 12 V supply and ground to power the switch, and connected the output to the control lines used to power the inductors on the battery pack relays.
In general, this update helped to clear up lots of space on the PCB. We did not fully redo the board this time, instead opting to clean up traces where we removed parts. We did move the power switches to the top of the board instead of the bottom, which enabled for easier testing since they were now the only way of closing the battery pack relays. We also added some extra parts that were included for our power filtering circuit in the bottom left-hand side of the board.