LPC824 microcontroller ADC demo HardFault problem - embedded

Question

I'm trying to program LPC824 microcontroller board ([https://www.switch-science.com/catalog/2265/][1]) with LPCOpen.
I'm using it with LPCLink 2 debugger board.
My goal is to get some information from the "pressure sensor" with an ADC.
My code stops with a HardFault when executing a NVIC_EnableIRQ function(on line: 92).
If I don't use "NVIC interrupt controller" then my code works and I can get value from sensor with ADC.
What I am doing wrong?
Here is my adc.c code:
#include "board.h"
static volatile int ticks;
static bool sequenceComplete = false;
static bool thresholdCrossed = false;
#define TICKRATE_HZ (100) /* 100 ticks per second */
#define BOARD_ADC_CH 2
/**
* #brief Handle interrupt from ADC sequencer A
* #return Nothing
*/
void ADC_SEQA_IRQHandler(void) {
uint32_t pending;
/* Get pending interrupts */
pending = Chip_ADC_GetFlags(LPC_ADC);
/* Sequence A completion interrupt */
if (pending & ADC_FLAGS_SEQA_INT_MASK) {
sequenceComplete = true;
}
/* Threshold crossing interrupt on ADC input channel */
if (pending & ADC_FLAGS_THCMP_MASK(BOARD_ADC_CH)) {
thresholdCrossed = true;
}
/* Clear any pending interrupts */
Chip_ADC_ClearFlags(LPC_ADC, pending);
}
/**
* #brief Handle interrupt from SysTick timer
* #return Nothing
*/
void SysTick_Handler(void) {
static uint32_t count;
/* Every 1/2 second */
if (count++ == TICKRATE_HZ / 2) {
count = 0;
Chip_ADC_StartSequencer(LPC_ADC, ADC_SEQA_IDX);
}
}
/**
* #brief main routine for ADC example
* #return Function should not exit
*/
int main(void) {
uint32_t rawSample;
int j;
SystemCoreClockUpdate();
Board_Init();
/* Setup ADC for 12-bit mode and normal power */
Chip_ADC_Init(LPC_ADC, 0);
Chip_ADC_Init(LPC_ADC, ADC_CR_MODE10BIT);
/* Need to do a calibration after initialization and trim */
Chip_ADC_StartCalibration(LPC_ADC);
while (!(Chip_ADC_IsCalibrationDone(LPC_ADC))) {
}
/* Setup for maximum ADC clock rate using sycnchronous clocking */
Chip_ADC_SetClockRate(LPC_ADC, ADC_MAX_SAMPLE_RATE);
Chip_ADC_SetupSequencer(LPC_ADC, ADC_SEQA_IDX,
(ADC_SEQ_CTRL_CHANSEL(BOARD_ADC_CH) | ADC_SEQ_CTRL_MODE_EOS));
Chip_Clock_EnablePeriphClock(SYSCTL_CLOCK_SWM);
Chip_SWM_EnableFixedPin(SWM_FIXED_ADC2);
Chip_Clock_DisablePeriphClock(SYSCTL_CLOCK_SWM);
/* Setup threshold 0 low and high values to about 25% and 75% of max */
Chip_ADC_SetThrLowValue(LPC_ADC, 0, ((1 * 0xFFF) / 4));
Chip_ADC_SetThrHighValue(LPC_ADC, 0, ((3 * 0xFFF) / 4));
Chip_ADC_ClearFlags(LPC_ADC, Chip_ADC_GetFlags(LPC_ADC));
Chip_ADC_EnableInt(LPC_ADC,
(ADC_INTEN_SEQA_ENABLE | ADC_INTEN_OVRRUN_ENABLE));
Chip_ADC_SelectTH0Channels(LPC_ADC, ADC_THRSEL_CHAN_SEL_THR1(BOARD_ADC_CH));
Chip_ADC_SetThresholdInt(LPC_ADC, BOARD_ADC_CH, ADC_INTEN_THCMP_CROSSING);
/* Enable ADC NVIC interrupt */
NVIC_EnableIRQ(ADC_SEQA_IRQn);
Chip_ADC_EnableSequencer(LPC_ADC, ADC_SEQA_IDX);
SysTick_Config(SystemCoreClock / TICKRATE_HZ);
/* Endless loop */
while (1) {
/* Sleep until something happens */
__WFI();
if (thresholdCrossed) {
thresholdCrossed = false;
printf("********ADC threshold event********\r\n");
}
/* Is a conversion sequence complete? */
if (sequenceComplete) {
sequenceComplete = false;
/* Get raw sample data for channels 0-11 */
for (j = 0; j < 12; j++) {
rawSample = Chip_ADC_GetDataReg(LPC_ADC, j);
/* Show some ADC data */
if (rawSample & (ADC_DR_OVERRUN | ADC_SEQ_GDAT_DATAVALID)) {
printf("Chan: %d Val: %d\r\n", j, ADC_DR_RESULT(rawSample));
printf("Threshold range: 0x%x ",
ADC_DR_THCMPRANGE(rawSample));
printf("Threshold cross: 0x%x\r\n",
ADC_DR_THCMPCROSS(rawSample));
printf("Overrun: %s ",
(rawSample & ADC_DR_OVERRUN) ? "true" : "false");
printf("Data Valid: %s\r\n\r\n",
(rawSample & ADC_SEQ_GDAT_DATAVALID) ?
"true" : "false");
}
}
}
}
}

Answer 1

Hard fault usually means that you try to execute code outside allowed addresses. If you have not registered the interrupt in the vector table but enabled it, the MCU will jump to whatever address that's written there instead, after which the program crashes.
How to fix that depends on tool chain. Assuming LPCXpresso, you have several options to set up libraries (I don't know about LPCOpen specifically), so where to find the vector table is different from case to case. However, this works quite similar on most MCUs, ARM or not. Somewhere in a "crt start-up" file you should have something along the lines of this:
void (* const g_pfnVectors[])(void) = ...
This is an array of function pointers which will be the vector table allocated in memory at address 0 on Cortex M. You have to place your function at the relevant interrupt vector. For example it may say something like
PIN_INT0_IRQHandler, // PIO INT0
If that's the interrupt you should implement, then you replace that line:
#include "my_irq_stuff.h"
...
void (* const g_pfnVectors[])(void) =
...
my_INT0, // PIO INT0
Assuming my_irq_stuff.h contains the function prototype my_INT0 for the interrupt service routine. The actual routine should be implemented in the corresponding .c file.