Arm Breakout Board (2024)
- Josh Magder
- Yuchen Lin
The following document will give a brief outline for the purpose of the Arm breakout board.
List of sensors: 08-21 Project Arm Sync
Purpose
The arm breakout board acts as a middle point between the encoders and limit switches on the arm with the Jetson in the Electrical Box. The arm board will reduce the number of electrical wires running down the arm, creating more free space.
System diagram:
Components
The arm board will feature a network of 6 small STM32 F042K6 boards which will each receive:
2 SSI/SPI signal for an encoder (Axis 2, 3, 5, 6) or 1 SPI signal for an encoder (Axis 1, 4)
4 Limit switches (basic GPIO digital signal input)
Each small board will send a packet through UART to one central F446
This board will be responsible for reading all 4 UART packets and creating one long message which will contain all sensor data. The message will be sent through an onboard CAN transceiver.
The F446 will act as a CAN repeater to determine if the data will be transmit to the jetson. The transmission model will be based on request and reply. There will be a USB(UART → USB) interface reserved for communication if needed.
The boards will all be soldered as through-hole components to the breakout board, where each signal on the STM board will be routed to an external pin on the breakout board. Using off-the-shelf nucleo is for time-saving reasons. The debugging interface will be using SWDIO; if possible, please follow the 20-pin JTAG flat ribbon connection convention. https://www.st.com/resource/en/user_manual/dm00026748-st-link-v2-in-circuit-debugger-programmer-for-stm8-and-stm32-stmicroelectronics.pdf
This board can assume to take 5V input from the box RS232 connector, since proper power distribution from 24V and step down to 5V takes a lot of effort to ensure the board works. 24V input variant is not considered in this iteration.
Sample breakout board (just for a rough understanding of how it would work):
