Hierarchical Firmware’s Design And Implementation For Thermal Printer

Hierarchical firmware is designed especially for thermal printer, and it includes basic print control system and special function for thermal print technology. After a carefully requirement analysis, this paper describes the design principle of hierarchical firmware and implementation method.The basic principle for firmware’s design is keeping hierarchical and modular to improve the extensibility and reusability. Thus, any changes of one module can hardly affect others. For example, by separating applications and system functions, we can only adjust applications when applying this system to another platform. The key modules include orders analysis, memory management and file management.In order to address more complicated print control process, we introduce a novel theory named event-based task management. For replacing print control with task management, this method makes system development more efficient. Furthermore, it ensures tasks scheduling only occurs when it is necessary, and it also decreases the times of task context switching.To fulfill the requires of executes continuously for thermal print process, we introduce a novel strategy that both tasks and interrupt service routines need to apply allowance from tasks scheduler before they begin to run. For keeping the quality of print process, print task cannot be preempted by other tasks. As we all know, interrupt service routines have a higher priority and can preempt the system’s control easily. Thus, we need take tasks and interrupt service routines under unified management to decide which task runs.By now, our hierarchical firmware for thermal printer has been widely used and it performs very stable. As our firmware has been designed with high hierarchical and modular, it can be easily extended when need to face new changes, and it also decreases the high expensive for system maintenance.