This project implements a robust CAN-Bus 2.0B communication network between two different STM32 families (F103RBT6 Nucleo as Master and F103C8T6 BluePill as Diagnostic Node). The system utilizes an interrupt-driven architecture to simulate real-time automotive data transmission, such as engine RPM and temperature.
- Master Node: STM32F103RBT6 Nucleo-64.
- Diagnostic Node: STM32F103C8T6 BluePill.
- Transceivers: 2x SN65HVD230 CAN Transceivers.
- Programmer: On-board ST-LINK v2.1 (from Nucleo).
One of the unique aspects of this project is using a single Nucleo board to program both itself and the BluePill node by utilizing the ST-LINK bridge.
- Jumper Configuration: Remove the two CN2 jumpers on the Nucleo to isolate the ST-LINK. Ensure a jumper is placed on JP1 for stable power delivery.
- Wiring (CN4 Header): Connect the BluePill to the Nucleo's CN4 header using the following pinout (Top-down, USB port at the top):
- Pin 2: SWCLK
- Pin 4: SWDIO (SWO)
- Pin 5: Reset (Connect to BluePill's NRST)
- Software Setup: * Generate the
.hexfile in STM32CubeIDE after a successful build.- Open STM32CubeProgrammer, go to the "Erase & Programming" tab, and select your hex file.
- Click Start Programming (Ensure "Verify programming" and "Run after programming" are checked for stability).
- Disconnect the header wires from the BluePill.
- Replace the two CN2 mini-jumpers to reconnect the ST-LINK to the Nucleo's main MCU.
- Flash the Master code directly via STM32CubeIDE.
During the initial stages, the system failed to communicate. The following hardware-level optimizations were implemented to achieve 100% stability:
- Problem: Attempting to power the SN65HVD230 transceivers from the BluePill's 3.3V pin caused communication failure. The BluePill's on-board LDO was insufficient for the transceiver's current spikes.
- Solution: Both CAN transceivers must be powered directly from the Nucleo’s power rails. Additionally, powering the BluePill with 5V from the Nucleo (instead of 3.3V) provided better stability for its internal regulators.
- Problem: Floating signals caused "No-ACK" errors.
- Solution: Established a strict Common Ground between the Nucleo, BluePill, and both CAN modules. Even if multiple GND connections seem redundant, they are essential for automotive signal integrity.
- Problem: High CPU overhead during continuous data polling.
- Solution: Implemented CAN RX Interrupts. The BluePill now stays in a low-load state and only processes data when a specific Message ID (0x123) is detected, mimicking a real ECU's behavior.
- Baud Rate: 125 kbps with optimized Sampling Point (%88).
- Event-Driven: LED toggling based on successful CAN frame reception.
- Data Structuring: Simulated RPM (16-bit) and Temperature (8-bit) data packets.
Author: [Yunus Kunduz] Electrical and Electronics Engineering Student | Embedded Systems Enthusiast