change system clock @Stellaris howto

[pao 0]

Hi all,

I'm testing system clock frequency.

 

 

 

1) change board.txt

    (energia_dir)\hardware\lm4f\boards.txt

######################################################
# Tiva C TM4C1233H6PM 80MHz
# with launchpad
######################################################
lpTivaC-1.name=Tiva C w/ TM4C1233H6PM (80MHz)
lpTivaC-1.upload.maximum_size=262144
lpTivaC-1.build.mcu=cortex-m4
lpTivaC-1.build.f_cpu=80000000L
lpTivaC-1.build.core=lm4f
lpTivaC-1.build.variant=stellarpad
lpTivaC-1.ldscript=lm4fcpp.ld

######################################################
# Tiva C TM4C1233H6PM 25MHz
# with launchpad
######################################################
lpTivaC-2.name=Tiva C w/ TM4C1233H6PM (25MHz)
lpTivaC-2.upload.maximum_size=262144
lpTivaC-2.build.mcu=cortex-m4
lpTivaC-2.build.f_cpu=25000000L
lpTivaC-2.build.core=lm4f
lpTivaC-2.build.variant=stellarpad
lpTivaC-2.ldscript=lm4fcpp.ld

2) change wireing.c,

    (energia_dir)\hardware\lm4f\cores\lm4f\wiring.c

void timerInit()
{

#if F_CPU >= 80000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_2_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 50000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_4|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 40000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 25000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_8|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 16000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_12_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 8000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_25|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#elif F_CPU >= 4000000
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_50|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#else
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_2_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|
                SYSCTL_OSC_MAIN);
#endif
    //
    // Run at system clock at 80MHz
    //

    //
    // SysTick is used for delay() and delayMicroseconds()
    //
// ROM_SysTickPeriodSet(0x00FFFFFF);
    ROM_SysTickPeriodSet(ROM_SysCtlClockGet() / TICKS_PER_SECOND);
    ROM_SysTickEnable();

.....
}

 

unsigned long micros(void)
{
    volatile unsigned int conMz = ROM_SysCtlClockGet()/1000/1000;
// return (milliseconds * 1000) + (HWREG(TIMER5_BASE + TIMER_O_TAV) / 80);
return (milliseconds * 1000) + (HWREG(TIMER5_BASE + TIMER_O_TAV) / conMz);
}

void delayMicroseconds(unsigned int us)
{
    volatile unsigned int conMz = ROM_SysCtlClockGet()/1000/1000;
volatile unsigned long elapsedTime;
unsigned long startTime = HWREG(NVIC_ST_CURRENT);
do{
elapsedTime = startTime-(HWREG(NVIC_ST_CURRENT) & 0x00FFFFFF);
}
// while(elapsedTime <= us*80);
while(elapsedTime <= us*conMz );
}

3) check clock @ Stellaris LaunchPad

//
// Check System Clock
//
//

#include "Energia.h"
#include "inc/hw_ints.h"
#include "inc/hw_nvic.h"
#include "inc/hw_sysctl.h"
#include "inc/hw_types.h"
#include "inc/hw_timer.h"

#include "driverlib/rom.h"
#include "driverlib/cpu.h"
#include "driverlib/debug.h"
#include "driverlib/interrupt.h"
#include "driverlib/timer.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"



void setup()
{
  Serial.begin(38400);
  pinMode( PUSH1, INPUT_PULLUP );
  pinMode( PUSH2, INPUT_PULLUP );
  
}

uint32_t system_clock;
uint32_t tick_value;

void loop()
{
  // put your main code here, to run repeatedly:
  system_clock = SysCtlClockGet()/1000;
  
  Serial.println( system_clock );
  tick_value = ROM_SysTickPeriodGet();
  Serial.println( tick_value );
  
  tone( BLUE_LED,500,100);
  delay(1000);
  
}