Hi @jingpan
As mentioned above in the post, I implemented the same in software and tried to test but it doesn't work.
The following is the program (I used acmp_interrupt program and modified it little but to suit my requirements)
#include "fsl_acmp.h"
#include "fsl_debug_console.h"
#include "pin_mux.h"
#include "clock_config.h"
#include "board.h"
/*******************************************************************************
* Definitions
******************************************************************************/
#define DEMO_ACMP_BASEADDR CMP0
#define DEMO_ACMP_USER_CHANNEL 0U
#define DEMO_ACMP_IRQ_ID CMP0_IRQn
#define DEMO_ACMP_IRQ_HANDLER_FUNC CMP0_IRQHandler
#define LED_INIT() LED_GREEN1_INIT(LOGIC_LED_OFF)
#define LED_ON() LED_GREEN1_ON()
#define LED_OFF() LED_GREEN1_OFF()
#define RISING_THRESHOLD 103u // 2V
#define FALLING_THRESHOLD 51u // 1V
/*******************************************************************************
* Prototypes
******************************************************************************/
/*******************************************************************************
* Variables
******************************************************************************/
volatile uint32_t g_acmpOutputRising = 0U;
volatile uint32_t g_acmpOutputFalling = 0U;
volatile uint8_t g_edge = 0u;
volatile uint32_t rising_error = 0u;
volatile uint32_t falling_error = 0u;
acmp_config_t acmpConfigStruct;
acmp_channel_config_t channelConfigStruct;
acmp_dac_config_t dacConfigStruct;
/*******************************************************************************
* Code
******************************************************************************/
static void Custom_ACMP_Init( void );
static void Custom_ACMP_ReInit( uint8_t edge_type );
void DEMO_ACMP_IRQ_HANDLER_FUNC(void)
{
uint32_t statusFlags = 0u;
statusFlags = ACMP_GetStatusFlags(DEMO_ACMP_BASEADDR);
ACMP_ClearStatusFlags(DEMO_ACMP_BASEADDR, statusFlags);
if( g_edge == 0u )
{
if ((kACMP_OutputAssertEventFlag == (statusFlags & kACMP_OutputAssertEventFlag)) &&
(kACMP_OutputRisingEventFlag == (statusFlags & kACMP_OutputRisingEventFlag)))
{
g_acmpOutputRising = 1U;
}
else
{
rising_error++;
}
// Reconfigure
Custom_ACMP_ReInit(1);
g_edge = 1u;
}
else if( g_edge == 1u )
{
if ((kACMP_OutputAssertEventFlag != (statusFlags & kACMP_OutputAssertEventFlag)) &&
(kACMP_OutputFallingEventFlag == (statusFlags & kACMP_OutputFallingEventFlag)))
{
g_acmpOutputFalling = 1U;
}
else
{
falling_error++;
}
Custom_ACMP_ReInit(0);
g_edge = 0u;
}
SDK_ISR_EXIT_BARRIER;
}
/*!
* @brief Main function
*/
int main(void)
{
BOARD_InitBootPins();
BOARD_InitBootClocks();
BOARD_InitDebugConsole();
LED_INIT();
LED_OFF();
Custom_ACMP_Init();
PRINTF("The example compares analog input to the reference DAC output(CMP negative port).\r\n");
PRINTF("The LED will be turned ON/OFF when the analog input is HIGHER/LOWER than the DAC output.\r\n");
PRINTF("Change the analog input voltage to see the LED status.\r\n");
while (true)
{
/* Check the comparison result and toggle the LED according to the result. */
if (g_acmpOutputRising)
{
g_acmpOutputRising = 0U;
LED_ON();
PRINTF("The analog input is HIGHER than DAC output\r\n");
}
else if (g_acmpOutputFalling)
{
g_acmpOutputFalling = 0U;
LED_OFF();
PRINTF("The analog input is LOWER than DAC output\r\n");
}
else
{
/* Unknown status. */
}
}
}
static void Custom_ACMP_Init( void )
{
ACMP_GetDefaultConfig(&acmpConfigStruct);
acmpConfigStruct.hysteresisMode = kACMP_HysteresisLevel3;
ACMP_Init(DEMO_ACMP_BASEADDR, &acmpConfigStruct);
channelConfigStruct.positivePortInput = kACMP_PortInputFromMux;
channelConfigStruct.negativePortInput = kACMP_PortInputFromDAC;
channelConfigStruct.minusMuxInput = 0U; /* Dummy channel. */
channelConfigStruct.plusMuxInput = DEMO_ACMP_USER_CHANNEL;
ACMP_SetChannelConfig(DEMO_ACMP_BASEADDR, &channelConfigStruct);
/* Configure DAC. */
dacConfigStruct.referenceVoltageSource = kACMP_VrefSourceVin1;
dacConfigStruct.DACValue = RISING_THRESHOLD; //0x7FU; /* Half of referene voltage. */
#if defined(FSL_FEATURE_ACMP_HAS_C1_DACOE_BIT) && (FSL_FEATURE_ACMP_HAS_C1_DACOE_BIT == 1U)
dacConfigStruct.enableOutput = true;
#endif /* FSL_FEATURE_ACMP_HAS_C1_DACOE_BIT */
#if defined(FSL_FEATURE_ACMP_HAS_C1_DMODE_BIT) && (FSL_FEATURE_ACMP_HAS_C1_DMODE_BIT == 1U)
dacConfigStruct.workMode = kACMP_DACWorkLowSpeedMode;
#endif /* FSL_FEATURE_ACMP_HAS_C1_DMODE_BIT */
ACMP_SetDACConfig(DEMO_ACMP_BASEADDR, &dacConfigStruct);
/* Enable the interrupts. */
// ACMP_EnableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputRisingInterruptEnable | kACMP_OutputFallingInterruptEnable);
ACMP_EnableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputRisingInterruptEnable );
EnableIRQ(DEMO_ACMP_IRQ_ID);
ACMP_Enable(DEMO_ACMP_BASEADDR, true);
}
static void Custom_ACMP_ReInit( uint8_t edge_type )
{
ACMP_Enable(DEMO_ACMP_BASEADDR, false);
/* Configure DAC. */
if( edge_type == 0u )
{
dacConfigStruct.DACValue = RISING_THRESHOLD;
}
else
{
dacConfigStruct.DACValue = FALLING_THRESHOLD;
}
ACMP_SetDACConfig(DEMO_ACMP_BASEADDR, &dacConfigStruct);
/* Enable the interrupts. */
if( edge_type == 0u )
{
ACMP_DisableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputFallingInterruptEnable);
ACMP_EnableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputRisingInterruptEnable);
}
else
{
ACMP_DisableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputRisingInterruptEnable);
ACMP_EnableInterrupts(DEMO_ACMP_BASEADDR, kACMP_OutputFallingInterruptEnable);
}
EnableIRQ(DEMO_ACMP_IRQ_ID);
ACMP_Enable(DEMO_ACMP_BASEADDR, true);
}
The flow is as below.
- At Power-Up, configure the CMP for Rising Edge
- When Rising Edge is received, Disable the CMP
- Update the DAC value for Falling Edge
- Enable the Falling Interrupt and Disable the Rising Interrupt
- Repeat the same steps for Rising Edge
But when I do so, the first rising edge is okay, but as soon as I tried to change the DAC value, and reconfigure the module, the next interrupt occurs immediately.
After debugging I found the following scenarios.
I disabled the Comparator Module, before updating the DAC value, and here CFF bit is set (my understanding is, since we disabled the module, Comparator Output changes from High -> Low, hence this happens)
After updating the DAC value for falling edge, I enabled the Comparator, and due to the my setup position, COUT is now 1 again, and hence CFR bit is also set.
And this messed up by simple state-machine.
But if I run my code by commenting the line ACMP_Enable(DEMO_ACMP_BASEADDR, false);, everything works fine, for obvious reason.
Can you please suggest, should I proceed without disabling the module?
The reason I disabled the module is because I am changing the DAC values and enabling only one type of interrupt at a time.
Thanks @jingpan
So if we don't disabled the comparator module, it works fine.
At the moment I am using a Potentiometer and rotating it manually, even I moved it very fast and everything was fine.
But when I applied my actual signal, which will looks like this.
I found that the variables in the else part of the interrupt handler i.e. "rising_error" and "falling_error" keeps on incrementing sometimes, not so fast but the pattern is uneven.
Does this means that the Comparator is not so fast enough to handle this type of signals, my signal frequency is 50Hz and can go till 60Hz, but as of now I am just testing with 50Hz.
Can you please suggest something here?
Thanks in advance.
