ComparatorIn - KL25Z Comparator library

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Frank Vannieuwkerke / ComparatorIn

KL25Z Comparator library

Dependents: ComparatorIn_demo TEMT6200_demo 05_comparator_demo 05_comparator_demo ... more

KL25Z Comparator library

Comparator features

Operational over the entire supply range
Inputs may range from rail to rail
Programmable hysteresis control
Selectable interrupt on rising-edge, falling-edge, or both rising or falling edges of the comparator output
Selectable inversion on comparator output
Capability to produce a wide range of outputs such as:
- Sampled
- Windowed, which is ideal for certain PWM zero-crossing-detection applications
- Digitally filtered:
  - Filter can be bypassed
  - Can be clocked via external SAMPLE signal or scaled bus clock
External hysteresis can be used at the same time that the output filter is used for internal functions
Two software selectable performance levels:
- Shorter propagation delay at the expense of higher power
- Low power, with longer propagation delay
DMA transfer support ^{not yet implemented in this library}
- A comparison event can be selected to trigger a DMA transfer
Functional in all modes of operation
The window and filter functions are not available in the following modes:
- Stop
- VLPS
- LLS
- VLLSx

Block diagram

/media/uploads/frankvnk/kl25z_comparator_block_diagram.jpg

Introduction

This library allows us to create comparator objects between different inputs.
The comparator + and - inputs can be routed to one out of eight reference inputs (see table).
Input selection

Pin name	#	MUX input	CMP0	Comment
PTC6	000	IN0	CMP0_IN0
PTC7	001	IN1	CMP0_IN1
PTC8	010	IN2	CMP0_IN2
PTC9	011	IN3	CMP0_IN3
PTE30	100	IN4	CMP0_IN4	12-bit DAC0
PTE29	101	IN5	CMP0_IN5
	110	IN6		1V internal Bandgap*
NC	111	IN7		internal 6-bit DAC0
(table 1)

* Not yet implemented

Using the library

Selecting pins on initialisation
Upon initialisation, the comparator registers are set to following values:

    CMP0->CR0   = 0x00;  // Filter and digital hysteresis disabled
    CMP0->CR1   = 0x17;  // Continuous mode, high-speed compare, unfiltered output, output pin disabled
    CMP0->FPR   = 0x00;  // Filter disabled
    CMP0->SCR   = 0x06;  // Disable all interrupts and clear flags (flags are cleared by this write)
    CMP0->DACCR = 0xE0;  // DAC enabled, Vdd is 6bit reference, threshold set to 1/2 of full-scale (1.65V)

The library accepts two input parameters:
example:

ComparatorIn compi(PTC8, NC);

First parameter : + input pin.
Second parameter : - input pin.
Every pin from the 'Pin name' column in (table 1) can be selected.

notes

IN6 (internal 1V bandgap reference) has no pin name and is not selectable on init.
However, we can use the SwitchPlus and SwitchMin functions to change the corresponding input to IN6.
There are two special cases for the input parameters:
- NC : Connect the internal 6-bit DAC0 to IN7.
- PTE30 : configures PTE30 as 12-bit DAC0 output and connect to IN4.
  IMPORTANT: Make sure no external output is connected to PTE30 when you declare this pin, otherwise you WILL destroy the external device and/or the CPU.

Example
Following code demonstrates interrupt callback and polling mode.
Note: Polling the comparator this way won't always trigger the printf because of the wait() instructions (if we go above and below the threshold during the wait() time, then the polling cannot not see this change).

/***********************************************************
CODE EXAMPLE FOR AMBIENT LIGHT SENSOR ON KL25Z + Wi-Go BOARD
 ***********************************************************/
#include "ComparatorIn.h"
#include "mbed.h"

DigitalOut blinker(LED_BLUE);
DigitalOut cmpled(LED_GREEN);
DigitalOut cmp_en (PTD5);
AnalogIn cmp_lvl (PTB0);
ComparatorIn compi(PTC8, NC); // in+ = PTC8, in- = internal 6-bit DAC 

// Comparator callback functions
void cmp_rise_ISR(void)
{
    cmpled = 0;
}

void cmp_fall_ISR(void)
{
    cmpled = 1;
}

int main()
{
    cmp_en = 1;
    cmpled = 1;

    compi.rising(&cmp_rise_ISR);                // Set pointer to rising interrupt function
    compi.falling(&cmp_fall_ISR);               // Set pointer to falling interrupt function
    compi.treshold(0.5);                        // Set comparator threshold to 1.65V = 32 * 3.3V / 64

    while(1)
    {
        printf("Light sensor : %7.5f Volt\n",cmp_lvl*3.3);
        blinker = 1;
        wait(1);
        blinker = 0;
        wait(0.2);
        if (compi.status() == 0x01)
        {
            printf("*** Treshold reached : %7.5f\n",cmp_lvl*3.3);
        }
    }
}

Notes

When we enable the comparator interrupt, we need to declare user callback function(s) (rising and/or falling interrupt) AND initialise the function pointer(s).
example:

compi.rising(&cmp_rise_ISR);
compi.falling(&cmp_fall_ISR);

Currently, following functions are not yet implemented:
- On the fly MUX switching for + input (SwitchPlus function).
- On the fly MUX switching for - input (SwitchMin function).
- DMA transfer.

Diff: ComparatorIn.cpp

Revision:: 0:e742ad3d7dac
Child:: 1:ccac56d8f1cb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ComparatorIn.cpp	Wed Jun 05 15:42:41 2013 +0000
@@ -0,0 +1,217 @@
+#include "ComparatorIn.h"
+ 
+void (*user_fptr)(unsigned int);    // Pointer to user function - called after IRQ assertion.
+
+const PinMap ComparatorIn::PinMap_CMP[] = {
+    {PTC6,  CMP0_IN0, 0},
+    {PTC7,  CMP0_IN1, 0},
+    {PTC8,  CMP0_IN2, 0},
+    {PTC9,  CMP0_IN3, 0},
+    {PTE30, CMP0_IN4, 0},       // ADC0_SE23
+    {PTE29, CMP0_IN5, 0},       // ADC0_SE4b
+    {NC,    NC,       0}
+};
+ 
+ComparatorIn::ComparatorIn(PinName pinP, PinName pinM)
+{
+    user_fptr = NULL;
+    CMPnumberP = (CMPName)pinmap_peripheral(pinP, PinMap_CMP);
+    if (CMPnumberP == (uint32_t)NC)         // When NC, use DAC0
+        CMPnumberP = 0x07;
+    CMPnumberM = (CMPName)pinmap_peripheral(pinM, PinMap_CMP);
+    if (CMPnumberM == (uint32_t)NC)         // When NC, use DAC0
+        CMPnumberM = 0x07;
+
+    SIM->SCGC4 |=SIM_SCGC4_CMP_MASK; // Enable HSCMP module clock
+
+    //Enable HSCMP0 Compare Out signal on PTC5
+//    PORTC_PCR5=PORT_PCR_MUX(6);  //CMP0_OUT on DIAG PTC5
+
+    hscmp_clear();
+    CMP0->CR0   = 0x00;  // Filter and digital hysteresis disabled
+    CMP0->CR1   = 0x17;  // Continuous mode, high-speed compare, unfiltered output, output pin disabled
+    CMP0->FPR   = 0x00;  // Filter disabled
+    CMP0->SCR   = 0x16;  // Enable rising edge interrupt and flag (flags are cleared by this write)
+    CMP0->DACCR = 0xC4;  // DAC enabled, Vdd is 6bit reference, threshold set to 1/16 of full-scale (0.2V)
+    CMP0->MUXCR = (CMPnumberP << 3) | (CMPnumberM & 0x07);  // P-input/M-input are ext.channels defined by CMPnumberP/CMPnumberN
+//    CMP0->CR1  |= CMP_CR1_OPE_MASK; // Enable output pin for HSCMP0
+
+    if(CMPnumberP < 6) pinmap_pinout(pinP, PinMap_CMP); //Map pins
+    if(CMPnumberM < 6) pinmap_pinout(pinM, PinMap_CMP); //Map pins
+};
+ 
+void ComparatorIn::filter_count(unsigned char fico)
+{
+    if((fico > 0) && (fico < 8))
+    {
+        unsigned char tmp;
+        tmp = (CMP0->CR0 & 0x70) | fico;            // Mask old value
+        CMP0->CR0 = tmp;                            // Set filter count
+    }
+}
+
+void ComparatorIn::hysteresis(unsigned char hyst)
+{
+    if(hyst < 4)
+    {
+        unsigned char tmp;
+        tmp = (CMP0->CR0 & 0x03) | hyst;            // Mask old value
+        CMP0->CR0 = tmp;                            // Set hysteresis
+    }
+}
+
+void ComparatorIn::sample_mode(unsigned char samp_en)
+{
+    if((CMP0->CR1 & CMP_CR1_WE_MASK) == 0)                  // Only allow change when window mode is inactive
+    {
+        if(samp_en == 1) CMP0->CR1 |= CMP_CR1_SE_MASK;      // Enable
+        else CMP0->CR1 &= ~CMP_CR1_SE_MASK;                 // Disable
+    }
+}
+
+void ComparatorIn::window_mode(unsigned char win_en)
+{
+    if((CMP0->CR1 & CMP_CR1_SE_MASK) == 0)                  // Only allow change when sample mode is inactive
+    {
+        if(win_en == 1) CMP0->CR1 |= CMP_CR1_WE_MASK;       // Enable
+        else CMP0->CR1 &= ~CMP_CR1_WE_MASK;                 // Disable
+    }
+}
+
+void ComparatorIn::trig_mode(unsigned char trig_en)
+{
+    if(trig_en == 1) CMP0->CR1 |= CMP_CR1_TRIGM_MASK;       // Enable
+    else CMP0->CR1 &= ~CMP_CR1_TRIGM_MASK;                  // Disable
+}
+
+void ComparatorIn::power_mode(unsigned char pmode)
+{
+    if(pmode == 1) CMP0->CR1 |= CMP_CR1_PMODE_MASK;      // Set high speed
+    else CMP0->CR1 &= ~CMP_CR1_PMODE_MASK;               // Set low speed
+}
+
+void ComparatorIn::invert(unsigned char inv)
+{
+    if(inv == 1) CMP0->CR1 |= CMP_CR1_INV_MASK;          // Enable
+    else CMP0->CR1 &= ~CMP_CR1_INV_MASK;                 // Disable
+}
+
+void ComparatorIn::output_select(unsigned char cos)
+{
+    if(cos == 1) CMP0->CR1 |= CMP_CR1_COS_MASK;          // Enable
+    else CMP0->CR1 &= ~CMP_CR1_COS_MASK;                 // Disable
+}
+
+void ComparatorIn::output_pin_en(unsigned char ope)
+{
+    if(ope == 1) CMP0->CR1 |= CMP_CR1_OPE_MASK;          // Enable
+    else CMP0->CR1 &= ~CMP_CR1_OPE_MASK;                 // Disable
+}
+
+void ComparatorIn::enable(unsigned char en)
+{
+    if(en == 1) CMP0->CR1 |= CMP_CR1_EN_MASK;            // Enable
+    else CMP0->CR1 &= ~CMP_CR1_EN_MASK;                  // Disable
+}
+
+void ComparatorIn::filter_period(unsigned char fipe)
+{
+    CMP0->FPR = CMP_FPR_FILT_PER(fipe);
+}
+
+void ComparatorIn::dma_en(unsigned char dmaen)
+{
+    if(dmaen == 1) CMP0->SCR |= CMP_SCR_DMAEN_MASK;      // Enable
+    else CMP0->SCR &= ~CMP_SCR_DMAEN_MASK;               // Disable
+}
+
+void ComparatorIn::int_en_rising(unsigned char ier)
+{
+    if(ier == 1) CMP0->SCR |= CMP_SCR_IER_MASK;          // Enable
+    else CMP0->SCR &= ~CMP_SCR_IER_MASK;                 // Disable
+}
+
+void ComparatorIn::int_en_falling(unsigned char ief)
+{
+    if(ief == 1) CMP0->SCR |= CMP_SCR_IEF_MASK;          // Enable
+    else CMP0->SCR &= ~CMP_SCR_IEF_MASK;                 // Disable
+}
+
+unsigned char ComparatorIn::status(void)
+{
+    return (CMP0->SCR & 0x01);
+}
+
+void ComparatorIn::dac_en(unsigned char den)
+{
+    if(den == 1) CMP0->DACCR |= CMP_DACCR_DACEN_MASK;    // Enable
+    else CMP0->DACCR &= ~CMP_DACCR_DACEN_MASK;           // Disable
+}
+
+void ComparatorIn::ref_source(unsigned char res)
+{
+    if(res == 1) CMP0->DACCR |= CMP_DACCR_VRSEL_MASK;    // Enable
+    else CMP0->DACCR &= ~CMP_DACCR_VRSEL_MASK;           // Disable
+}
+
+void ComparatorIn::treshold(unsigned char vo_sel)
+{
+    if(vo_sel < 64)
+    {
+        unsigned char tmp;
+        tmp = (CMP0->DACCR & 0xC0) | vo_sel;             // Mask old value
+        CMP0->DACCR = tmp;                               // Set Vout DAC to vo_sel
+    }
+}
+
+void ComparatorIn::pass_through(unsigned char ptm)
+{
+    if(ptm == 1) CMP0->MUXCR |= CMP_MUXCR_MSEL_MASK;     // Enable
+    else CMP0->MUXCR &= ~CMP_MUXCR_MSEL_MASK;            // Disable
+}
+
+void ComparatorIn::switch_plus(unsigned char pinP)
+{
+}
+ 
+void ComparatorIn::switch_min(unsigned char pinM)
+{
+}
+ 
+void ComparatorIn::hscmp_clear(void)
+{
+  CMP0->CR0   = 0;
+  CMP0->CR1   = 0;
+  CMP0->FPR   = 0;
+  CMP0->SCR   = 0x06;  // Clear flags if set.
+  CMP0->DACCR = 0;
+  CMP0->MUXCR = 0;
+}
+
+void ComparatorIn::_callbackISR(void(*fptr)(unsigned int))  
+{
+    NVIC_SetVector(CMP0_IRQn, (uint32_t)&_cmpISR);  // Set comparator ISR to _cmpISR routine
+    NVIC_EnableIRQ(CMP0_IRQn);                      // Enable comparator ISR
+    user_fptr = fptr;
+}
+
+void ComparatorIn::_cmpISR(void)  
+{
+    // clear interrupt flags by reading them
+    //If rising edge
+    if (((CMP0->SCR & CMP_SCR_IER_MASK)==CMP_SCR_IER_MASK) && ((CMP0->SCR & CMP_SCR_CFR_MASK)==CMP_SCR_CFR_MASK))
+    {
+        CMP0->SCR |= CMP_SCR_CFR_MASK;  // Clear the flag
+        if (user_fptr != NULL) user_fptr(CMP_SCR_CFR_MASK);
+    }
+
+    //If falling edge
+    if (((CMP0->SCR & CMP_SCR_IEF_MASK)==CMP_SCR_IEF_MASK) && ((CMP0->SCR & CMP_SCR_CFF_MASK)==CMP_SCR_CFF_MASK))
+    {
+        CMP0->SCR |= CMP_SCR_CFF_MASK;  // Clear the flag
+        if (user_fptr != NULL) user_fptr(CMP_SCR_CFF_MASK);
+    }
+    // call user function 
+}
+
+

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Repository details

Type:	Library
Created:	05 Jun 2013
Imports:	137
Forks:	0
Commits:	20
Dependents:	5
Dependencies:	0
Followers:	9
Issues:	0

The code in this repository is MIT licensed.

KL25Z Comparator library

Comparator features

Block diagram

Introduction

Using the library

Diff: ComparatorIn.cpp

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