css_cmake_test/f2833x/examples/lpm_standbywake/Example_2833xStandbyWake.c

//###########################################################################
//
// FILE:	Example_2833xStandbyWake.c
//
// TITLE:	Low Power Modes: Device Standby Mode and Wakeup Example
//
//!  \addtogroup f2833x_example_list
//!  <h1>Low Power Modes: Device Standby Mode and Wakeup (lpm_standbywake)</h1>
//!
//!  This example puts the device into STANDBY mode. If the lowest
//!  possible current consumption in STANDBY mode is desired, the
//!  JTAG connector must be removed from the device board while
//!  the device is in STANDBY mode.
//!
//!  GPIO0 is configured as the LPM wakeup pin to trigger a
//!  WAKEINT interrupt upon detection of a low pulse.
//!  Initially, pull GPIO0 high externally. To wake device
//!  from standby mode, pull GPIO0 low for at least (2+QUALSTDBY)
//!  OSCLKS, then pull it high again.
//!
//!  The example then wakes up the device from STANDBY using GPIO0.
//!  GPIO0 wakes the device from STANDBY mode when a low pulse
//!  (signal goes high->low->high)is detected on the pin.
//!  This pin must be pulsed by an external agent for wakeup.
//!
//!  As soon as GPIO0 goes high again after the pulse, the device
//!  should wake up, and GPIO1 can be observed to toggle.
//!
//! \b External \b Connections \n
//!  - To observe when device wakes from STANDBY mode, monitor
//!    GPIO1 with an oscilloscope (set to 1 in WAKEINT ISR)
//
//###########################################################################
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//###########################################################################

//
// Included Files
//
#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File

//
// Function Prototypes
//
__interrupt void WAKE_ISR(void);  	// ISR for WAKEINT

//
// Main
//
void main()
{
    //
    // Step 1. Initialize System Control:
    // PLL, WatchDog, enable Peripheral Clocks
    // This example function is found in the DSP2833x_SysCtrl.c file.
    //
    InitSysCtrl();

    //
    // Step 2. Initialize GPIO:
    // This example function is found in the DSP2833x_Gpio.c file and
    // illustrates how to set the GPIO to it's default state.
    //
    // InitGpio();  // Skipped for this example

    EALLOW;
    GpioCtrlRegs.GPAPUD.all = 0;            // Enable all Pull-ups
    GpioCtrlRegs.GPBPUD.all = 0;
    
    //
    // GPIO1 set in the ISR to indicate device woken up.
    //
    GpioCtrlRegs.GPADIR.bit.GPIO1 = 1;
    
    GpioIntRegs.GPIOLPMSEL.bit.GPIO0 = 1;	// Choose GPIO0 pin for wakeup
    EDIS;

    //
    // Step 3. Clear all interrupts and initialize PIE vector table:
    // Disable CPU interrupts
    //
    DINT;

    //
    // Initialize the PIE control registers to their default state.
    // The default state is all PIE interrupts disabled and flags
    // are cleared.
    // This function is found in the DSP2833x_PieCtrl.c file.
    //
    InitPieCtrl();

    //
    // Disable CPU interrupts and clear all CPU interrupt flags:
    //
    IER = 0x0000;
    IFR = 0x0000;

    //
    // Initialize the PIE vector table with pointers to the shell Interrupt
    // Service Routines (ISR).
    // This will populate the entire table, even if the interrupt
    // is not used in this example.  This is useful for debug purposes.
    // The shell ISR routines are found in DSP2833x_DefaultIsr.c.
    // This function is found in DSP2833x_PieVect.c.
    //
    InitPieVectTable();

    //
    // Interrupts that are used in this example are re-mapped to
    // ISR functions found within this file.
    //
    EALLOW;  // This is needed to write to EALLOW protected registers
    PieVectTable.WAKEINT = &WAKE_ISR;
    EDIS;

    //
    // Step 4. Initialize all the Device Peripherals:
    // Not applicable for this example.
    //

    //
    // Step 5. User specific code, enable interrupts
    //

    //
    // Enable CPU INT1 which is connected to WakeInt
    //
    IER |= M_INT1;

    //
    // Enable WAKEINT in the PIE: Group 1 interrupt 8
    //
    PieCtrlRegs.PIEIER1.bit.INTx8 = 1;
    PieCtrlRegs.PIEACK.bit.ACK1 = 1;
    
    //
    // Enable global Interrupts
    //
    EINT;                       // Enable Global interrupt INTM

    //
    // Choose qualification cycles in LPMCR0 register
    //
    
    //
    // The wakeup signal should be (2+QUALSTDBY) OSCCLKs wide.
    //
    SysCtrlRegs.LPMCR0.bit.QUALSTDBY = 0;

    //
    // Write the LPM code value
    //
    EALLOW;
    
    //
    // Only enter Standby mode when PLL is not in limp mode.
    //
    if (SysCtrlRegs.PLLSTS.bit.MCLKSTS != 1)
    {
        SysCtrlRegs.LPMCR0.bit.LPM = 0x0001;   // LPM mode = Standby
    }
    EDIS;

    //
    // Force device into STANDBY
    //
    
    //
    // Device waits in IDLE until falling edge on GPIO0/XNMI pin
    // wakes device from Standby mode.
    //
    __asm(" IDLE");
    
    //
    // Loop here after wake-up.
    //
    for(;;)
    {
        
    }
}

//
// ISR for WAKEINT - Will be executed when low pulse triggered on GPIO0 pin
//
__interrupt void 
WAKE_ISR(void)
{
    //
    // Toggle GPIO1 in the ISR - monitored with oscilloscope
    //
    GpioDataRegs.GPATOGGLE.bit.GPIO1 = 1;
    PieCtrlRegs.PIEACK.bit.ACK1 = 1;
}

//
// End of File
//