Senior DesignSoftware-1Seattle Pacific University High-level Software Design Context Diagram Connections between major components Synchronization with external events Polling or interrupts Major software structures Device drivers Bridge between HW and SW

Senior DesignSoftware-2Seattle Pacific University Context Diagram Show software connections between components Indicate which drivers are needed Indicate where interrupt handlers are needed RTC Buttons EEROM LCD A/D RS232 Example for logging meter (Interrupt Driven) MCU Read Data Change Mode Store Data Set Clock Send Data to PC Display Data Driver I/H Driver I/H Data Control Main Loop (Do nothing) Reset (To all Drivers)

Senior DesignSoftware-3Seattle Pacific University External Synchronization External events may be discovered in two ways Polling  Check for new data on a regular basis  Main program has to integrate polls into the main loop Interrupts  External events announce themselves  Must carefully write interrupt handlers  Main program doesn’t have to be aware of what is going on with interrupts Choices If your product is driven mostly by external events, use interrupt-driven If your produce systematically goes through processes, use polling

Senior DesignSoftware-4Seattle Pacific University Device Drivers Interface between hardware and software Provide a package of easy-to-use subroutines to control and transfer data to external device Main software never “touches” I/O ports – instead uses device driver subroutines Benefits If hardware changes, only the device driver changes, not the main software Programmers don’t have to understand the details of all of the hardware Consistent methods of accessing and controlling external devices

Senior DesignSoftware-5Seattle Pacific University Software Architecture Document Introduction Explain the role of software in your product Context diagram Draw a diagram showing how the major hardware components of your system are connected with software  Indicate where device drivers and interrupt handlers will be used Software structure overview Describe major control flow  Interrupt-driven, polling, hybrid, etc… Include rationale for your choice

Senior DesignSoftware-6Seattle Pacific University Software Architecture Document Main software routines Describe main software routines  Purpose, inputs, outputs and effects Include diagrams when useful Device drivers (separate document, due later) Describe software interface to each device driver  List all driver subroutines including parameters  Describe data structures needed Indicate which MCU port pins/busses will be used for each hardware component