Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER# AT90CAN12816MU Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The AT90CAN12816MU is a high-performance 8-bit AVR microcontroller with integrated CAN controller, making it particularly suitable for:
Industrial Control Systems
- Real-time process control applications
- Distributed sensor networks
- Motor control systems
- PLC (Programmable Logic Controller) implementations
Automotive Applications
- Body control modules
- Dashboard instrumentation
- Climate control systems
- Door and window control units
Building Automation
- HVAC system controllers
- Lighting control systems
- Security and access control
- Energy management systems
Medical Equipment
- Patient monitoring devices
- Diagnostic equipment interfaces
- Therapeutic device controllers
### Industry Applications
Automotive Industry
- Advantages : Built-in CAN 2.0A/B controller with 15 message objects, robust communication in noisy environments
- Limitations : Limited processing power for complex automotive infotainment systems
- Typical Implementation : Used in electronic control units (ECUs) requiring CAN bus communication
Industrial Automation
- Advantages : 128KB flash memory accommodates complex control algorithms, 4KB EEPROM for parameter storage
- Limitations : 8-bit architecture may be insufficient for high-speed data processing applications
- Implementation : Factory automation controllers, robotic control interfaces
Medical Devices
- Advantages : Low-power modes extend battery life, reliable communication for critical systems
- Limitations : May require additional safety certifications for medical applications
- Use Case : Portable medical monitoring equipment with communication capabilities
### Practical Advantages and Limitations
Advantages
- Integrated CAN Controller : Eliminates need for external CAN controllers, reducing BOM cost and PCB space
- Large Memory : 128KB flash and 4KB SRAM support complex applications
- Robust Communication : CAN interface provides reliable data transmission in noisy environments
- Low Power Operation : Multiple sleep modes for power-sensitive applications
- Rich Peripheral Set : Multiple timers, USART, SPI, and TWI interfaces
Limitations
- 8-bit Architecture : Limited computational power for intensive processing tasks
- Clock Speed : Maximum 16MHz may be insufficient for high-speed applications
- Memory Constraints : 4KB SRAM may limit complex data structures in large applications
- Package Complexity : 64-pin QFN package requires careful PCB design and assembly
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Power Supply Design
- Pitfall : Inadequate decoupling causing erratic behavior
- Solution : Implement 100nF ceramic capacitors at each power pin, plus bulk 10μF tantalum capacitors
- Implementation : Place decoupling capacitors within 5mm of power pins
Clock Circuit Issues
- Pitfall : Crystal oscillator failing to start or unstable operation
- Solution : Use appropriate load capacitors (typically 22pF) and ensure proper PCB layout
- Implementation : Keep crystal and capacitors close to microcontroller, avoid routing other signals nearby
CAN Bus Implementation
- Pitfall : Communication errors due to improper termination
- Solution : Implement 120Ω termination resistors at both ends of CAN bus
- Implementation : Use CAN transceiver (e.g., MCP2551) with proper common-mode choke
### Compatibility Issues
Voltage Level Compatibility
- Issue : 5V I/O pins may not be compatible with 3.3V systems
- Solution : Use level shifters or select 3.3V compatible peripherals
- Alternative : Configure I/O pins for appropriate drive strength
CAN Transceiver Selection
- Compatible Transceivers : MCP2551, TJA1050, SN65HVD230
- Consider
