// TI File $Revision: /main/7 $
// Checkin $Date: September 20, 2007 13:30:31 $
//###########################################################################
//
// FILE: DSP2833x_SysCtrl.c
//
// TITLE: DSP2833x Device System Control Initialization & Support Functions.
//
// DESCRIPTION:
//
// Example initialization of system resources.
//
//###########################################################################
// $TI Release: DSP2833x Header Files V1.01 $
// $Release Date: September 26, 2007 $
//###########################################################################
#include "DSP2833x_Device.h" // Headerfile Include File
#include "DSP2833x_Examples.h" // Examples Include File
// Functions that will be run from RAM need to be assigned to
// a different section. This section will then be mapped to a load and
// run address using the linker cmd file.
//#pragma CODE_SECTION(InitFlash, "ramfuncs");
//---------------------------------------------------------------------------
// InitSysCtrl:
//---------------------------------------------------------------------------
// This function initializes the System Control registers to a known state.
// - Disables the watchdog
// - Set the PLLCR for proper SYSCLKOUT frequency
// - Set the pre-scaler for the high and low frequency peripheral clocks
// - Enable the clocks to the peripherals
void InitSysCtrl(void)
{
// Disable the watchdog
DisableDog();
// Initialize the PLL control: PLLCR and DIVSEL
// DSP28_PLLCR and DSP28_DIVSEL are defined in DSP2833x_Examples.h
InitPll(DSP28_PLLCR,DSP28_DIVSEL);
// Initialize the peripheral clocks
InitPeripheralClocks();
}
//---------------------------------------------------------------------------
// Example: InitFlash:
//---------------------------------------------------------------------------
// This function initializes the Flash Control registers
// CAUTION
// This function MUST be executed out of RAM. Executing it
// out of OTP/Flash will yield unpredictable results
void InitFlash(void)
{
EALLOW;
//Enable Flash Pipeline mode to improve performance
//of code executed from Flash.
FlashRegs.FOPT.bit.ENPIPE = 1;
// CAUTION
//Minimum waitstates required for the flash operating
//at a given CPU rate must be characterized by TI.
//Refer to the datasheet for the latest information.
#if CPU_FRQ_150MHZ
//Set the Paged Waitstate for the Flash
FlashRegs.FBANKWAIT.bit.PAGEWAIT = 5;
//Set the Random Waitstate for the Flash
FlashRegs.FBANKWAIT.bit.RANDWAIT = 5;
//Set the Waitstate for the OTP
FlashRegs.FOTPWAIT.bit.OTPWAIT = 8;
#endif
#if CPU_FRQ_100MHZ
//Set the Paged Waitstate for the Flash
FlashRegs.FBANKWAIT.bit.PAGEWAIT = 3;
//Set the Random Waitstate for the Flash
FlashRegs.FBANKWAIT.bit.RANDWAIT = 3;
//Set the Waitstate for the OTP
FlashRegs.FOTPWAIT.bit.OTPWAIT = 5;
#endif
// CAUTION
//ONLY THE DEFAULT VALUE FOR THESE 2 REGISTERS SHOULD BE USED
FlashRegs.FSTDBYWAIT.bit.STDBYWAIT = 0x01FF;
FlashRegs.FACTIVEWAIT.bit.ACTIVEWAIT = 0x01FF;
EDIS;
//Force a pipeline flush to ensure that the write to
//the last register configured occurs before returning.
asm(" RPT #7 || NOP");
}
//---------------------------------------------------------------------------
// Example: ServiceDog:
//---------------------------------------------------------------------------
// This function resets the watchdog timer.
// Enable this function for using ServiceDog in the application
void ServiceDog(void)
{
EALLOW;
SysCtrlRegs.WDKEY = 0x0055;
SysCtrlRegs.WDKEY = 0x00AA;
EDIS;
}
//---------------------------------------------------------------------------
// Example: DisableDog:
//---------------------------------------------------------------------------
// This function disables the watchdog timer.
void DisableDog(void)
{
EALLOW;
SysCtrlRegs.WDCR= 0x0068;
EDIS;
}
//---------------------------------------------------------------------------
// Example: InitPll:
//---------------------------------------------------------------------------
// This function initializes the PLLCR register.
void InitPll(Uint16 val, Uint16 divsel)
{
// Make sure the PLL is not running in limp mode
if (SysCtrlRegs.PLLSTS.bit.MCLKSTS != 0)
{
// Missing external clock has been detected
// Replace this line with a call to an appropriate
// SystemShutdown(); function.
asm(" ESTOP0");
}
// DIVSEL MUST be 0 before PLLCR can be changed from
// 0x0000. It is set to 0 by an external reset XRSn
// This puts us in 1/4
if (SysCtrlRegs.PLLSTS.bit.DIVSEL != 0)
{
EALLOW;
SysCtrlRegs.PLLSTS.bit.DIVSEL = 0;
EDIS;
}
// Change the PLLCR
if (SysCtrlRegs.PLLCR.bit.DIV != val)
{
EALLOW;
// Before setting PLLCR turn off missing clock detect logic
SysCtrlRegs.PLLSTS.bit.MCLKOFF = 1;
SysCtrlRegs.PLLCR.bit.DIV = val;
EDIS;
// Optional: Wait for PLL to lock.
// During this time the CPU will switch to OSCCLK/2 until
// the PLL is stable. Once the PLL is stable the CPU will
// switch to the new PLL value.
//
// This time-to-lock is monitored by a PLL lock counter.
//
// Code is not required to sit and wait for the PLL to lock.
// However, if the code does anything that is timing critical,
// and requires the correct clock be locked, then it is best to
// wait until this switching has completed.
// Wait for the PLL lock bit to be set.
// The watchdog should be disabled before this loop, or fed within
// the loop via ServiceDog().
// Uncomment to disable the watchdog
DisableDog();
while(SysCtrlRegs.PLLSTS.bit.PLLLOCKS != 1)
{
// Uncomment to service the watchdog
// ServiceDog();
}
EALLOW;
SysCtrlRegs.PLLSTS.bit.MCLKOFF = 0;
EDIS;
}
// If switching to 1/2
if((divsel == 1)||(divsel == 2))
{
EALLOW;
SysCtrlRegs.PLLSTS.bit.DIVSEL = divsel;
EDIS;
}
// If switching to 1/1
// * First go to 1/2 and let the power settle
// The time required will depend on the system, this is only an example
// * Then switch to 1/1
if(divsel == 3)
{
EALLOW;
SysCtrlRegs.PLLSTS.bit.DIVSEL = 2;
DELAY_US(50L);
SysCtrlRegs.PLLSTS.bit.DIVSEL = 3;
EDIS;
}
}
//--------------------------------------------------------------------------
// Example: InitPeripheralClocks:
//---------------------------------------------------------------------------
// This function initializes the clocks to the peripheral modules.
// First the high and low clock prescalers are set
// Second the clocks are enabled to each peripheral.
// To reduce power, leave clocks to unused peripherals disabled
//
// Note: If a peripherals clock is not enabled then you cannot
// read or write to the registers for that peripheral
void InitPeripheralClocks(void)
{
EALLOW;
// HISPCP/LOSPCP prescale register settings, normally it will be set to default values
SysCtrlRegs.HISPCP.all = 0x0001;
SysCtrlRegs.LOSPCP.all = 0x0002;
// XCLKOUT to SYSCLKOUT ratio. By default XCLKOUT = 1/4 SYSCLKOUT
// XTIMCLK = SYSCLKOUT/2
XintfRegs.XINTCNF2.bit.XTIMCLK = 1;
// XCLKOUT = XTIMCLK/2
XintfRegs.XINTCNF2.bit.CLKMODE = 1;
// Enable XCLKOUT
XintfRegs.XINTCNF2.bit.CLKOFF = 0;
// Peripheral clock enables set for the selected peripherals.
// If you are not using a peripheral leave the clock off
// to save on power.
//
// Note: not all peripherals are available on all 2833x derivates.
// Refer to the datasheet
