Real-Time Payment Announcement System
Developed firmware for a cost-effective payment sound box using Quectel EC800KCN module with 4MB RAM/ROM. The system receives payment notifications via MQTT, dynamically downloads audio files over HTTPS, and plays them in real-time without requiring external memory storage.
Design a cost-effective payment sound box that can play real-time payment announcements without external memory, using only 4MB RAM/ROM while supporting dynamic audio file downloads and playback.
Implemented a streaming audio architecture using ThreadX RTOS with MQTT for notifications, HTTPS for audio downloads, and I2S for real-time audio playback, all within the 4MB memory constraint.
Reduced hardware costs by 40% by eliminating external memory requirements while maintaining real-time audio playback performance for payment notifications ranging from 10KB to 100KB files.
Dynamic audio download and playback without external storage
Reliable cellular communication with MQTT and HTTPS protocols
Efficient operation within 4MB RAM/ROM constraints
Delta and full firmware update capabilities
40% reduction in hardware costs
Real-time audio streaming without external memory
Support for 10KB to 100KB audio files
Reliable 4G LTE connectivity
Successful OTA update implementation
Production deployment in payment systems
Interactive visualization showing the complete device boot sequence and system initialization process.
ThreadX RTOS • 4G LTE • MQTT Protocol
System Boot
ThreadX RTOS initialization
4G LTE Connection
Cellular connectivity establishment
MQTT Protocol
Payment broker connection
Ready State
Payment notification listener