DSP Microcomputers# ADSP21MSP59 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The ADSP21MSP59 is a mixed-signal processor specifically designed for voice processing applications where analog and digital signal processing coexist. Primary use cases include:
- Voice compression/decompression systems implementing algorithms like G.711, G.723.1, and GSM
- Echo cancellation circuits in telecommunication equipment
- Voice mail systems requiring both recording and playback capabilities
- Digital answering machines with message storage and retrieval
- Voice recognition front-ends for command and control systems
### Industry Applications
Telecommunications Sector:
- Digital telephone systems (PBX, key systems)
- Voice-over-IP (VoIP) gateways and terminals
- Cellular base station voice processing
- Conference bridge systems
Consumer Electronics:
- Advanced telephone answering devices
- Voice memo recorders
- Interactive voice response (IVR) systems
- Home automation voice interfaces
Industrial Applications:
- Voice logging and recording systems
- Security system voice prompts
- Industrial equipment voice status reporting
### Practical Advantages and Limitations
Advantages:
- Integrated analog front-end eliminates need for external codec components
- Low power consumption (typically 60mW at 3.3V) suitable for portable applications
- Dual processor architecture allows simultaneous signal processing and system control
- On-chip program and data RAM reduces external memory requirements
- Flexible serial ports support multiple audio interface standards
Limitations:
- Fixed-point architecture may require careful scaling for complex algorithms
- Limited on-chip memory (2K words program RAM, 1K words data RAM) constrains application complexity
- Legacy 5V tolerant I/O may not be optimal for modern low-voltage systems
- Obsolete manufacturing process affects availability and cost-effectiveness compared to newer solutions
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Power Supply Sequencing:
- Pitfall : Applying I/O voltage before core voltage can cause latch-up
- Solution : Implement proper power sequencing with voltage supervisors
Clock Management:
- Pitfall : Unstable clock signals causing processor lock-up
- Solution : Use crystal oscillators with proper load capacitors and keep clock traces short
Analog Signal Integrity:
- Pitfall : Noise coupling into analog inputs degrading voice quality
- Solution : Implement proper grounding and shielding for analog sections
### Compatibility Issues
Mixed Voltage Systems:
- The ADSP21MSP59 operates with 3.3V core and 5V-tolerant I/O
- Interface considerations when connecting to modern 1.8V or 2.5V devices
- Level translation required for communication with lower voltage peripherals
Memory Interface:
- External memory timing must match processor's wait state requirements
- Bus contention possible during power-up if external devices aren't properly isolated
Serial Interface Timing:
- Clock synchronization critical when interfacing with other DSPs or codecs
- Data format compatibility must match connected devices (µ-law, A-law, linear)
### PCB Layout Recommendations
Power Distribution:
- Use star configuration for analog and digital power supplies
- Implement separate ground planes for analog and digital sections
- Place decoupling capacitors (0.1µF ceramic) within 5mm of each power pin
Signal Routing:
- Keep analog input traces short and away from digital switching signals
- Route clock signals with controlled impedance and minimal vias
- Use guard rings around sensitive analog inputs
Thermal Management:
- Provide adequate co
