ComparatorIn - KL25Z Comparator library

Users » frankvnk » Code » ComparatorIn

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:: 17:048474f28d28
Parent:: 15:f340e0545b53
Child:: 19:e6a4cd28e217

--- a/ComparatorIn.cpp	Sun Jun 16 20:05:23 2013 +0000
+++ b/ComparatorIn.cpp	Sat Jul 20 16:24:32 2013 +0000
@@ -22,7 +22,8 @@
     {PTE29, CMP0_IN5, 0},       // ADC0_SE4b
     {NC,    NC,       0}        // Internal 6-bit DAC0
 };
- 
+
+
 ComparatorIn::ComparatorIn(PinName pinP, PinName pinM)
 {
     rise_fptr = NULL;
@@ -50,9 +51,12 @@
     if((CMPnumberP == 4) || (CMPnumberM == 4)) _dac12 = new AnalogOut (PTE30);  // When PTE30 is selected, use it as 12-bit DAC
     
     NVIC_SetVector(CMP0_IRQn, (uint32_t)&_cmpISR);      // Set comparator ISR to _cmpISR routine
+    falling(NULL);                                      // set falling IRQ pointer to NULL
+    rising(NULL);                                       // set rising IRQ pointer to NULL
+    NVIC_DisableIRQ(CMP0_IRQn);                         // disable CMP0 IRQ
 };
  
-void ComparatorIn::filter_count(unsigned char fico)
+void ComparatorIn::FilterCount(unsigned char fico)
 {
     if((fico > 0) && (fico < 8))
     {
@@ -72,7 +76,7 @@
     }
 }
 
-void ComparatorIn::sample_mode(unsigned char samp_en)
+void ComparatorIn::SampleMode(unsigned char samp_en)
 {
     if((CMP0->CR1 & CMP_CR1_WE_MASK) == 0)                  // Only allow change when window mode is inactive
     {
@@ -81,7 +85,7 @@
     }
 }
 
-void ComparatorIn::window_mode(unsigned char win_en)
+void ComparatorIn::WindowMode(unsigned char win_en)
 {
     if((CMP0->CR1 & CMP_CR1_SE_MASK) == 0)                  // Only allow change when sample mode is inactive
     {
@@ -90,13 +94,13 @@
     }
 }
 
-void ComparatorIn::trig_mode(unsigned char trig_en)
+void ComparatorIn::TrigMode(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)
+void ComparatorIn::PowerMode(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
@@ -108,13 +112,13 @@
     else CMP0->CR1 &= ~CMP_CR1_INV_MASK;                 // Disable
 }
 
-void ComparatorIn::output_select(unsigned char cos)
+void ComparatorIn::OutputSelect(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(PinName ope)
+void ComparatorIn::OutputPin(PinName ope)
 {
     PinName pin_stat;
     pin_stat = op_status();                                  // Get pin status
@@ -140,12 +144,12 @@
     else CMP0->CR1 &= ~CMP_CR1_EN_MASK;                  // Disable
 }
 
-void ComparatorIn::filter_period(unsigned char fipe)
+void ComparatorIn::FilterPeriod(unsigned char fipe)
 {
     CMP0->FPR = CMP_FPR_FILT_PER(fipe);
 }
 
-void ComparatorIn::dma_en(unsigned char dmaen)
+void ComparatorIn::dma(unsigned char dmaen)
 {
     if(dmaen == 1) CMP0->SCR |= CMP_SCR_DMAEN_MASK;      // Enable
     else CMP0->SCR &= ~CMP_SCR_DMAEN_MASK;               // Disable
@@ -156,13 +160,13 @@
     return (CMP0->SCR & 0x01);
 }
 
-void ComparatorIn::dac_en(unsigned char den)
+void ComparatorIn::dac(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)
+void ComparatorIn::RefSource(unsigned char res)
 {
     if(res == 1) CMP0->DACCR |= CMP_DACCR_VRSEL_MASK;    // Enable
     else CMP0->DACCR &= ~CMP_DACCR_VRSEL_MASK;           // Disable
@@ -184,17 +188,17 @@
     }
 }
 
-void ComparatorIn::pass_through(unsigned char ptm)
+void ComparatorIn::PassThrough(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::SwitchPlus(unsigned char pinP)
 {
 }
  
-void ComparatorIn::switch_min(unsigned char pinM)
+void ComparatorIn::SwitchMin(unsigned char pinM)
 {
 }
  
@@ -208,22 +212,38 @@
   CMP0->MUXCR = 0;
 }
 
-void ComparatorIn::int_en(bool ien)
-{
-    if(ien) NVIC_EnableIRQ(CMP0_IRQn);                   // Enable comparator ISR
-    else NVIC_DisableIRQ(CMP0_IRQn);                     // Disable comparator ISR
-}
-
 void ComparatorIn::rising(void(*fptr)(void))
 {
-    rise_fptr = fptr;
-    CMP0->SCR |= (CMP_SCR_IER_MASK | CMP_SCR_CFR_MASK);  // Enable rising int. and clear flag
+    if(fptr == NULL)
+    {
+        CMP0->SCR &= ~CMP_SCR_IER_MASK;  // Disable rising int.
+        CMP0->SCR |=  CMP_SCR_CFR_MASK;  // clear flag
+        if(fall_fptr == NULL)
+            NVIC_DisableIRQ(CMP0_IRQn);
+    }
+    else
+    {
+        rise_fptr = fptr;
+        CMP0->SCR |= (CMP_SCR_IER_MASK | CMP_SCR_CFR_MASK);  // Enable rising int. and clear flag
+        NVIC_EnableIRQ(CMP0_IRQn);  // enable CMP0 interrupt
+    }
 }
-
+ 
 void ComparatorIn::falling(void(*fptr)(void))
 {
-    fall_fptr = fptr;
-    CMP0->SCR |= (CMP_SCR_IEF_MASK | CMP_SCR_CFF_MASK);  // Enable falling int. and clear flag
+    if(fptr == NULL)
+    {
+        CMP0->SCR &= ~CMP_SCR_IEF_MASK;  // Disable falling int.
+        CMP0->SCR |=  CMP_SCR_CFF_MASK;  // clear flag
+        if(rise_fptr == NULL)
+            NVIC_DisableIRQ(CMP0_IRQn);
+    }
+    else
+    {
+        fall_fptr = fptr;
+        CMP0->SCR |= (CMP_SCR_IEF_MASK | CMP_SCR_CFF_MASK);  // Enable falling int. and clear flag
+        NVIC_EnableIRQ(CMP0_IRQn);  // enable CMP0 interrupt
+    }
 }
 
 void ComparatorIn::_cmpISR(void)  
@@ -313,3 +333,4 @@
 }
 
 
+

Repository toolbox

Export to desktop IDE

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

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning