Interrupt

dsPIC30F dsPIC33F dsPIC33E dsPIC33C dsPIC33A PIC32

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The Interrupt block creates interrupt-driven subsystems by connecting peripheral interrupt sources to Simulink triggered subsystems. The block automatically manages interrupt vector configuration, priority levels, and timing synchronization. Key Capabilities: - Automatic interrupt detection - Discovers all peripheral interrupts in model - Dynamic interrupt list - Popup shows only available interrupts from active peripherals - Priority management - Configure interrupt priority levels (device-dependent) - Multiple timing modes - Base rate, periodic trigger, or hardware timer-based - Context preservation - Automatic FPU context save/restore (PIC32 with FPU)

Interrupt Sources

Peripheral Interrupts (Auto-detected)

The block automatically detects interrupts from peripheral blocks in your model:

User-Defined Interrupts

Peripheral blocks can define custom interrupts using MCHP_USER_INTERRUPTS parameter:

// In peripheral block RTWdata

Parameters format:
  VectorName(name)           % If new vector needed
  Config_BitSet(IECx=value)  % Interrupt enable bits
  RegisterReadClear(IFSx)    % Flag clear register
  Priority(level)            % Fixed priority or -1 for user config

Block Parameters

Interrupt Selection

Timing Configuration

Device-Specific Interrupt Configuration

dsPIC30F/33F/33E/33C/33A

PIC32 (MIPS)

SAM (ARM Cortex-M)

Examples

Example 1: ADC Interrupt-Driven Current Loop

// PWM triggers ADC, ADC interrupt executes control loop

Simulink Model:
1. Add PWM_HS block with ADC trigger output
2. Add ADC block with interrupt enabled
3. Add Interrupt block
4. Configure interrupt block:
   Interruption: 'ADC1 - Conversion Complete'
   Triggered_Sub_TimeSource: 'is derived from model base rate'
   IntPriority: 7  (highest - critical for motor control)

5. Create triggered subsystem connected to interrupt block
6. Add current control algorithm inside subsystem

Result: Current loop executes synchronously with PWM/ADC

Example 2: UART Receive Interrupt

// Process received data asynchronously

Configuration:
   Interruption: 'UART1 - RX'
   Triggered_Sub_TimeSource: 'is derived from trigs; trigs must be periodic'
   TrigsPeriod: 1e-3  % 1 ms assumed for timing (actual rate is async)
   IntPriority: 3  (medium priority)
   StartupExecute: on  (initialize buffers)

Subsystem:
- Read UART data from peripheral block
- Parse protocol
- Update command registers

Example 3: Hardware Timer Periodic Interrupt

// Custom periodic task independent of base rate

Configuration:
   Interruption: 'User Timer1'  (created by peripheral block)
   Triggered_Sub_TimeSource: 'is derived from a hardware timer'
   TIMER_Resolution: 'Resol: 32us - MaxPer: 2.1s'  (prescaler 256)
   IntPriority: 5

Result:
- Dedicated timer allocated automatically
- Interrupt triggers at specified rate
- Independent of Simulink sample times

Example 4: QEI Position Overflow Event

// Extend encoder range with software counter

Configuration:
   Interruption: 'QEI1 - Position Counter Overflow'
   Triggered_Sub_TimeSource: 'is derived from model base rate'
   IntPriority: 6  (high - timing critical)

Subsystem Logic:
if (QEI_DIR == FORWARD)
    ExtendedPosition += 65536;
else
    ExtendedPosition -= 65536;
end

Timing Modes Explained

Mode 1: Derived from Model Base Rate

• Subsystem sample time = model base rate
• Timing analysis uses base rate for schedulability
• Best for interrupts synchronized with main control loop
• Example: ADC conversion complete after PWM trigger

Mode 2: Derived from Periodic Trigs

• User specifies expected interrupt rate in TrigsPeriod
• Allows timing analysis for asynchronous interrupts
• Subsystem scheduled assuming periodic behavior
• Example: UART receive (assume max message rate)

Mode 3: Hardware Timer-Based

• Dedicated timer resource automatically allocated
• Timer configured with selected prescaler
• True periodic interrupt independent of Simulink rates
• Example: Custom 1 kHz update loop

Troubleshooting

        Keep ISR execution time short - long ISRs can cause overload
        Higher priority ISRs can preempt lower priority - ensure reentrancy
        Hardware timer mode consumes one timer resource
        StartupExecute useful for initializing communication protocols

See Also

• [MCHP_Scheduler_Options] - Multitasking scheduler configuration
• [MCHP_Master] - Clock and device configuration
• [MCHP_ADC_Universal] - ADC interrupt sources
• [MCHP_PWM_HS_FEP] - PWM event interrupts