TM4C123GH6PM Maximum ADC sample ratio.

I've been there a little research and I found that these two statements are equivalent, correct?

HWREG(ADC0_BASE + ADC_O_PC) = (ADC_PC_SR_1M);
ADCClockConfigSet(ADC0_BASE,  ADC_CLOCK_SRC_PLL | ADC_CLOCK_RATE_FULL, 1);

If i use "ADC_CLOCK_SRC_PIOSC" instead "ADC_CLOCK_SRC_PLL", the sample rate is not exactly 15.6250, its value ranges in 15.5xxx kHz. Perhaps it is because it uses the internal oscillator and no XTAL with PLL?

but equally I can not sample more than 15,6250 kHz.

What am I avoiding?

When I change the sampling rate to another value other than 64, to program the microcontroller, this does not start, do nothing, do not turn on the LEDs, nothing.

This is my code:

//#define TARGET_IS_TM4C123_RB1
//#define PART_TM4C123GH6PM

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <math.h>

//#include "inc/tm4c123gh6pm.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "inc/hw_ints.h"
#include "inc/hw_nvic.h"
#include "inc/hw_gpio.h"
#include "inc/hw_adc.h"

#include "driverlib/adc.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "driverlib/ssi.h"
#include "driverlib/pwm.h"
#include "driverlib/interrupt.h"
#include "driverlib/fpu.h"
#include "driverlib/rom.h"
#include "driverlib/rom_map.h"
#include "driverlib/systick.h"

#include "utils/uartstdio.h"

#include "Nokia5110.h"

// Defines
#define LED_RED GPIO_PIN_1
#define LED_BLUE GPIO_PIN_2
#define LED_GREEN GPIO_PIN_3

// Global variables
double Temp=0;
uint32_t adcValues[4];
uint32_t adcValue;

// Functions prototypes
void ROM_CLK_Init_80MHz(void);
void ROM_delay_ms(float ms);
void ROM_ADC_Init(void);
void ROM_UART_Init(void);
void ROM_SSI_Init(void);
void ROM_PWM_Init(void);
void ROM_SysTick_Init(void);

// Interrupts
void ADC0IntHandler(void)
{	
	ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, LED_RED);
	ROM_ADCIntClear(ADC0_BASE,1);
	//while(!ROM_ADCIntStatus(ADC0_BASE, 1, false));
	ROM_ADCSequenceDataGet(ADC0_BASE,1, &adcValue);
	
	//Temp= 147.5-((75*(3.3)*adcValue)/4096.f);
	ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, !LED_RED);	
}

void SysTickIntHandler(void)
{	
	ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, LED_RED);


	ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, !LED_RED);
}

int main(void)
{	
	uint32_t ui32ClockDiv;
	//Enable lazy stacking
	ROM_FPUEnable();
	ROM_FPULazyStackingEnable();
	
	ROM_CLK_Init_80MHz();
//	ROM_UART_Init();
	ROM_ADC_Init();
	ROM_SSI_Init();
	ROM_PWM_Init();
//	ROM_SysTick_Init();
	
	ROM_IntPrioritySet(INT_ADC0SS1, 0x00);
  ROM_IntPrioritySet(INT_SYSCTL, 0x01);
	
	ROM_IntMasterEnable();
	
	// Initialize the GPIO for the LED.
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
	ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN);
	
	// Set Nokia 5110 led light
	ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_2, 65535./100*100);		// 100% illumitation
	Nokia5110_Init();
	
	Nokia5110_Clear();
	Nokia5110_DrawFullImage(fernando);
	ROM_delay_ms(500);
  Nokia5110_Clear();
	
//	ROM_SysTickEnable();
	
	while(1)
	{
		// LED on
		ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, LED_BLUE);
		
		Nokia5110_SetCursor(2,0);
		Nokia5110_OutFloat33(147.5-((75*(3.3)*adcValue)/4096.f));
		Nokia5110_SetCursor(2,1);
		Nokia5110_OutU32Dec(ADCClockConfigGet(ADC0_BASE, &ui32ClockDiv));
		Nokia5110_SetCursor(2,2);
		Nokia5110_OutU32Dec(ui32ClockDiv);
		Nokia5110_SetCursor(2,3);
		Nokia5110_OutU32Dec(HWREG(ADC0_BASE + ADC_O_PP));
		
		ROM_delay_ms(100);

		// LED off
		ROM_GPIOPinWrite(GPIO_PORTF_BASE, LED_RED|LED_BLUE|LED_GREEN, !LED_BLUE);

		// Delay for second
		ROM_delay_ms(100);
		
	}
	
}

// Functions
void ROM_CLK_Init_80MHz(void)
{
	// Setup the system clock to run at 80 Mhz from PLL with crystal reference
	ROM_SysCtlClockSet(SYSCTL_SYSDIV_2_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
}

void ROM_delay_ms(float ms)
{
	ROM_SysCtlDelay((ROM_SysCtlClockGet()*(ms/1000.f))/3.f);
}

void ROM_SysTick_Init(void)
{
	ROM_SysTickPeriodSet(ROM_SysCtlClockGet()*0.1);  // 100ms, 10 Hz. Max 200 Hz, because SysClk=80Mhz and SysTick is 24 bits.
	SysTickIntRegister(SysTickIntHandler);
	ROM_SysTickIntEnable();
}

void ROM_ADC_Init(void)
{
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
	
	ROM_ADCHardwareOversampleConfigure(ADC0_BASE, 64);
	HWREG(ADC0_BASE + ADC_O_PC) = (ADC_PC_SR_1M);
//	ADCClockConfigSet(ADC0_BASE,  ADC_CLOCK_SRC_PLL | ADC_CLOCK_RATE_FULL, 1);
	
	
	ROM_ADCSequenceDisable(ADC0_BASE,1);
	ROM_ADCSequenceConfigure(ADC0_BASE,1, ADC_TRIGGER_ALWAYS,0);
//	ROM_ADCSequenceStepConfigure(ADC0_BASE,1,0,ADC_CTL_CH0);
//	ROM_ADCSequenceStepConfigure(ADC0_BASE,1,1,ADC_CTL_CH1);
//	ROM_ADCSequenceStepConfigure(ADC0_BASE,1,2,ADC_CTL_CH2);
	ROM_ADCSequenceStepConfigure(ADC0_BASE,1,0,ADC_CTL_TS|ADC_CTL_IE|ADC_CTL_END);
	ROM_ADCSequenceEnable(ADC0_BASE,1);
	
	ADCIntRegister(ADC0_BASE,1,ADC0IntHandler);
	ROM_IntEnable(INT_ADC0SS0);

  ROM_ADCIntEnable(ADC0_BASE,1);
  ROM_ADCIntClear(ADC0_BASE, 1);
}

void ROM_UART_Init(void)
{
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

	ROM_GPIOPinConfigure(GPIO_PA0_U0RX);
	ROM_GPIOPinConfigure(GPIO_PA1_U0TX);
	ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);

	ROM_UARTClockSourceSet(UART0_BASE, ROM_SysCtlClockGet());
	UARTStdioConfig(0, 1000000, ROM_SysCtlClockGet());
	}

void ROM_SSI_Init(void)
{
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
	
	ROM_GPIOPinConfigure(GPIO_PA2_SSI0CLK);
	ROM_GPIOPinConfigure(GPIO_PA3_SSI0FSS);
	ROM_GPIOPinConfigure(GPIO_PA4_SSI0RX);
	ROM_GPIOPinConfigure(GPIO_PA5_SSI0TX);
	
	ROM_GPIOPinTypeGPIOOutput(GPIO_PORTA_BASE, GPIO_PIN_6 | GPIO_PIN_7);
	ROM_GPIOPadConfigSet(GPIO_PORTA_BASE, GPIO_PIN_6 | GPIO_PIN_7, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD);
	
	ROM_GPIOPinTypeSSI(GPIO_PORTA_BASE, GPIO_PIN_5 | GPIO_PIN_4 | GPIO_PIN_3 | GPIO_PIN_2);
	ROM_SSIConfigSetExpClk(SSI0_BASE, ROM_SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
										 SSI_MODE_MASTER, 8000000, 8);
	
	ROM_SSIEnable(SSI0_BASE);
}
	
void ROM_PWM_Init(void)
{	
	//Configure PWM Clock to match system
	ROM_SysCtlPWMClockSet(SYSCTL_PWMDIV_1);

	// Enable the peripherals used by this program.
	//ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
	ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM1);

	//Configure PF1,PF2,PF3 Pins as PWM and PE4
	ROM_GPIOPinConfigure(GPIO_PE4_M1PWM2);
	//ROM_GPIOPinConfigure(GPIO_PF1_M1PWM5);
	//ROM_GPIOPinConfigure(GPIO_PF2_M1PWM6);
	//ROM_GPIOPinConfigure(GPIO_PF3_M1PWM7);
	//ROM_GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);
	ROM_GPIOPinTypePWM(GPIO_PORTE_BASE, GPIO_PIN_4);

	//Configure PWM Options
	//PWM_GEN_2 Covers M1PWM4 and M1PWM5
	//PWM_GEN_3 Covers M1PWM6 and M1PWM7 See page 207 4/11/13 DriverLib doc
	//ROM_PWMGenConfigure(PWM1_BASE, PWM_GEN_2, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
	//ROM_PWMGenConfigure(PWM1_BASE, PWM_GEN_3, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
	ROM_PWMGenConfigure(PWM1_BASE, PWM_GEN_1, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
	
	//Set the Period (expressed in clock ticks)
	//ROM_PWMGenPeriodSet(PWM1_BASE, PWM_GEN_2, 65536);
	//ROM_PWMGenPeriodSet(PWM1_BASE, PWM_GEN_3, 65536);
	ROM_PWMGenPeriodSet(PWM1_BASE, PWM_GEN_1, 65536);

	//Set PWM duty-00%
	//ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_5,0);
	//ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6,0);
	//ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_7,0);
	ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_2,0);

	// Enable the PWM generator
	//ROM_PWMGenEnable(PWM1_BASE, PWM_GEN_2);
	//ROM_PWMGenEnable(PWM1_BASE, PWM_GEN_3);
	ROM_PWMGenEnable(PWM1_BASE, PWM_GEN_1);

	// Turn on the Output pins
	//ROM_PWMOutputState(PWM1_BASE, PWM_OUT_5_BIT | PWM_OUT_6_BIT | PWM_OUT_7_BIT | PWM_OUT_2_BIT, true);
	ROM_PWMOutputState(PWM1_BASE, PWM_OUT_2_BIT, true);
}

Hi Amit, thanks!

Are well configured the peripherals?, is necessary some additional configuration?, why the access order produce different effects?

Regards,
Fernando.