MPC5746C Voltage Comparator

[cholland]

Please help,

I can't seem to get the Voltage Comparator to work.

I have tried most all the setups. Continuous mode, Sample Enable, Sample Enable + Filtered.

Nothing seems to work. I have tried varying the hard block Hysterisis control, etc.

I would like to note that; In continuous mode I setup Falling Edge Flag along with Falling Edge Interrupt.

The interrupt routine seems to be taking all the processors time.

All that is in the routine is just a counter variable. Nothing else.

Its just the opposite with Sample mode, the interrupt routine never gets called.

In this example, I am only trying see the output of the comparator.

void MCAL_CMP_init(void)
{

/* Configure CMP2_O pin */

SIUL2.MSCR[PB10].R = 0x0u;
SIUL2.MSCR[PB10].B.SRC = 0x3u;
SIUL2.MSCR[PB10].B.OBE = 0x1u;
SIUL2.MSCR[PB10].B.SSS = 0x3u;

/* Inputs are configured elsewhere. I am getting valid ADC readings on the input pins.

 * We are using the same pin for both ADC and CMP, but right now I have disabled the ADC

 * in order to verify that the voltage comparator works

 */

MCAL_CMP_2_config();

// Set Interrupt Priority
INTC.PSR[562].R = 0x8001; /* Vector # 562 Analogue_Comparator_Module_2 CMP2 */

// Finally Enable the Comparator
CMP_2.C0.B.EN = 1; /* Comparator Module Enable */
}

void MCAL_CMP_2_config(void)
{
/* Peripheral Control Register */
MC_ME.PCTL[22].B.RUN_CFG = 0x1; /* CMP_2 Peripheral Control Register */

/*---------------------------------------------------------------------------*/
/* REGISTER C0 */
/*---------------------------------------------------------------------------*/
CMP_2.C0.R = 0; /* Reset to a known state */
CMP_2.C0.B.DMAEN = 0; /* DMA Enable [Disable(0) Enable(1)]*/
CMP_2.C0.B.IER = 0; /* Interrupt Enable Rising */
CMP_2.C0.B.IEF = 0; /* Interrupt Enable Falling */
CMP_2.C0.B.CFR = 0; /* Comparator Flag Rising */
CMP_2.C0.B.CFF = 0; /* Comparator Flag Falling */
CMP_2.C0.B.FPR = 0; /* Filter Sample Period[8:15] (Dependent on CMP_2.C0.B.SE)*/
CMP_2.C0.B.SE = 0; /* Sample Enable */
CMP_2.C0.B.WE = 0; /* Window Enable */
CMP_2.C0.B.PMODE = 1; /* Power Mode Select (High Speed) */
CMP_2.C0.B.INVT = 0; /* Comparator Invert */
CMP_2.C0.B.COS = 1; /* Comparator Output Select [Filtered(0) or Unfiltered(1)] Miller Genuine Draft*/
CMP_2.C0.B.OPE = 1; /* Comparator Output Pin Enable */
CMP_2.C0.B.EN = 0; /* Comparator Module Enable (Disabled while configured) */
CMP_2.C0.B.FILTER_CNT = 0; /* Filter Sample Count [2:0] */
CMP_2.C0.B.HYSTCTR = 1; /* Comparator hard block hysteresis control */

/*---------------------------------------------------------------------------*/
/* REGISTER C1 */
/*---------------------------------------------------------------------------*/
CMP_2.C1.R = 0; /* Reset to a known state */
CMP_2.C1.B.CHN7 = 0; /* Channel 7 (23) Input Enable */
CMP_2.C1.B.CHN6 = 0; /* Channel 6 (22) Input Enable */
CMP_2.C1.B.CHN5 = 0; /* Channel 5 (21) Input Enable */
CMP_2.C1.B.CHN4 = 0; /* Channel 4 (20) Input Enable */
CMP_2.C1.B.CHN3 = 1; /* Channel 3 (19 LINE_1) Input Enable */
CMP_2.C1.B.CHN2 = 0; /* Channel 2 (18) Input Enable */
CMP_2.C1.B.CHN1 = 1; /* Channel 1 (17 LINE_2) Input Enable */
CMP_2.C1.B.CHN0 = 1; /* Channel 0 (16 LINE_3) Input Enable */
CMP_2.C1.B.DPSEL = 0; /* DAC output to Plus side ANMUX selection */
CMP_2.C1.B.DMSEL = 1; /* DAC output to Minus side ANMUX selection */
CMP_2.C1.B.PSEL = 3; /* Plus Input MUX Control (Reference Input 0) (Doesn't matter if DPSEL is 1)*/
CMP_2.C1.B.MSEL = 0; /* Minus Input MUX Control(Reference Input 1) (Doesn't matter if DMSEL is 1)*/
CMP_2.C1.B.DACEN = 1; /* DAC Enable */
CMP_2.C1.B.VRSEL = 0; /* Supply Voltage Reference Source Select (Vin1(0) or Vin2(1))*//* Package is LQFP176 */
CMP_2.C1.B.VOSEL = 32; /* DAC Output Voltage Select */ /* Right in the middle should be acceptable for verification */
/* (Vin/64) * (VOSEL + 1) */
/* (5/64) * (0 + 1) */ 
/* 0.078125 */

/*---------------------------------------------------------------------------*/
/* REGISTER C2 */
/*---------------------------------------------------------------------------*/
CMP_2.C2.R = 0; /* Reset to a known state */
CMP_2.C2.B.RRE = 0; /* Round-Robin Enable */
CMP_2.C2.B.RRIE = 0; /* Round-Robin interrupt enable */
CMP_2.C2.B.FXMP = 0; /* Fixed MUX Port (Plus Port(0) Minus Port(1) */
CMP_2.C2.B.FXDACI = 0; /* Fix DAC input to the fixed mux port side */
CMP_2.C2.B.FXMXCH = 0; /* Fixed channel selection */
CMP_2.C2.B.NSAM = 0; /* Number of sample clocks */
CMP_2.C2.B.ACOn = 0x0; /* The result of the input comparison for channel n. OR */
/* The preset state of Channel n */
}

/* The interrupt routine where in continuous mode seems to take all the processors time */

/* I have setup interrupt routines for various other peripherals, so It looks correct */

/* partial ISR file contents */

(uint32_t) &dummy, /* Vector # 560 Analogue_Comparator_Module_0 CMP0 */
(uint32_t) &dummy, /* Vector # 561 Analogue_Comparator_Module_1 CMP1 */
(uint32_t) &MCAL_CMP2_ISR, /* Vector # 562 Analogue_Comparator_Module_2 CMP2 */

void MCAL_CMP2_ISR(void)
{
CPM2Isr++;
}

Thanks for your help,

[cholland]

It works.

First, I didn't know I needed to enabled the input buffer. So I enabled it for the pin(s).

Second, I thought I had to enable the flags to enable the Interrupt. I was mistaken.

I set them to 0 in the configuration.

CMP_2.C0.B.CFR = 0; /* Comparator Flag Rising */
CMP_2.C0.B.CFF = 0; /* Comparator Flag Falling */

Then In the interrupt routine, I cleared the interrupts.

void MCAL_CMP2_ISR(void)
{
CPM2Isr++;

CMP_0.C0.B.CFR = 0; /* Comparator Flag Rising */
CMP_0.C0.B.CFF = 0; /* Comparator Flag Falling */
}

Sometimes you have to clear an interrupt to get the interrupt to fire again.

This is not the case for the voltage comparator.

If the interrupt is not cleared, the interrupt will take up all of the processor cycles, not allowing other processes to work.

Regards,