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µVision User's Guide

About µVision User Interface Creating Applications Debugging Start Debugging Start Energy Measurement without Debug Application Program Execution Debug Windows and Dialogs Breakpoints Window Call Stack and Locals Window Code Coverage Command Window Component Viewer Disassembly Window Editor Window Event Recorder Setup Event Recorder Event Recorder Window Events Filtering Event Statistics Window Post-mortem Analysis Event Viewer Execution Profiler Instruction Trace Window System Analyzer Usage tips Save System Analyzer Contents Statistics Restrictions Logic Analyzer Setup Setup in Detail Restrictions Cortex-M Trace Configuration Memory Map Memory Window Performance Analyzer Registers Window Serial Window Debug (printf) Viewer Symbols Window System Viewer Adding System Viewer Windows System and Thread Viewer Thread States Toolbox Trace Data Window Trace Navigation Trace Exceptions Event Counters ULINKplus Window Watch Window Core Peripherals Cortex-M0 and Cortex-M0+ Nested Vector Interrupt Controller System Control and Configuration System Tick Timer Fault Reports (Cortex-M0+ only) Cortex-M3, Cortex-M4, and Cortex-M7 Nested Vector Interrupt Controller System Control and Configuration System Tick Timer Fault Reports Memory Protection Unit Cortex-M23 and Cortex-M33 Nested Vector Interrupt Controller System Control and Configuration System Tick Timer Fault Reports Memory Protection Unit Security Attribution Unit Debug Scripting Expressions Constants System Variables Peripheral Variables I/O Ports Serial Ports Program Variables (Symbols) Fully Qualified Symbols Non-Qualified Symbols Literal Symbols Using Symbols Line Numbers Bit Addresses Type Specifications Memory Attribution Specifiers Operators Differences between µVision and C Expression Examples Code and Data Trace (Cortex-M) Trace Features Configuring Trace Tracepoint Expressions Tracepoint Intrinsics Tracepoint Limitations Tracepoint Marks Tips and Tricks Review Peripherals and CPU Configuration Simulate I/O Ports Simulate Interrupts and Clock Inputs Simulate external I/O Devices Assign Serial I/O to a PC COM Port Check Illegal Memory Access Command Input from File Preset I/O Ports or Memory Contents Write Debug Output to a File Keyboard Shortcuts TPIU Initialization after RESET (Cortex-M) Prevent Opening Files Show Japanese Messages Debug Commands Debug Functions Simulation Flash Programming Dialogs Utilities Command Line Example Programs Appendix

I/O Ports

µVision defines a VTREG for each I/O port: i.e. PORTA. Do not mix-up VTREGs with Peripheral Registers for each port (for example, PIOA_OSR). Peripheral Registers can be accessed inside the CPU memory space. VTREGs are signals present on the pins.

It is easy to simulate input from external hardware. If you have a pulse train coming into a port pin, you can use a Signal Function to simulate the signal. For example, the following Signal Function inputs a square wave on PORTA pin 0 with a frequency of 1000Hz.

signal void one_thou_hz (void) {
  while (1) {                      /* repeat forever       */
    PORTA |= 1;                    /* set PORTA bit 0      */
    swatch (0.0005);               /* delay for .0005 secs */
    PORTA &= ~1;                   /* clear PORTA bit 0    */
    swatch (0.0005);               /* delay for .0005 secs */
  }                                /* repeat               */
}

The following command starts this Signal Function:

one_thou_hz ()

Refer to µVision Debug Functions for more information about User- and Signal Functions.

Simulating hardware that responds to output from a port pin is slightly more difficult. Two steps are required. First, write a µVision User- or Signal Function to perform the desired operations. Second, create a breakpoint that invokes the user function.

Suppose you use an output pin (PORTA bit 0) to enable or disable a LED. The following Signal Function uses the PORT2 VTREG to check the output from the CPU and to display a message in the Command window.

signal void check_pA0 (void) {
  if (PORTA & 1)) {                            /* Test PORTA bit 0 */
    printf ("LED is ON\n"); }                  /* 1? LED is ON */
  else { /* 0? LED is OFF */
    printf ("LED is OFF\n"):
  }
}

Now, add a breakpoint. The following command line adds a breakpoint for all writes to PORT2.

BS WRITE PORT2, 1, "check_p20 ()"

Whenever your target program writes to PORT2, the check_P20 function prints the current status of the LED. Refer to Breakpoints for more information about setting breakpoints.

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