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.h

Revision:: 17:048474f28d28
Parent:: 16:18170968fdc3
Child:: 18:efa8d41b738f

--- a/ComparatorIn.h	Sun Jun 16 20:05:23 2013 +0000
+++ b/ComparatorIn.h	Sat Jul 20 16:24:32 2013 +0000
@@ -69,7 +69,7 @@
     * @param input Unsigned char - range : 1..7
     * @return none
     */
-    void filter_count(unsigned char fico);
+    void FilterCount(unsigned char fico);
 
     /** Set the hysteresis
     *
@@ -88,14 +88,14 @@
     * @param input Unsigned char (0 or 1)
     * @return none
     */
-    void sample_mode(unsigned char samp_en);
+    void SampleMode(unsigned char samp_en);
 
     /** Enable windowing mode
     * @param . Cannot be set when sampling mode is enabled
     * @param input Unsigned char (0 or 1)
     * @return none
     */
-    void window_mode(unsigned char win_en);
+    void WindowMode(unsigned char win_en);
 
     /** Enable trigger mode
     * @param . CMP and DAC are configured to CMP Trigger mode when CMP_CR1[TRIGM] is set to 1.
@@ -108,7 +108,7 @@
     * @param input Unsigned char (0 or 1)
     * @return none
     */
-    void trig_mode(unsigned char trig_en);
+    void TrigMode(unsigned char trig_en);
 
     /** Set the power mode
     * @param . 0 Low-Speed (LS) Comparison mode selected. In this mode, CMP has
@@ -118,7 +118,7 @@
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void power_mode(unsigned char pmode);
+    void PowerMode(unsigned char pmode);
 
     /** Set invert mode
     * @param . Allows selection of the polarity of the analog comparator function.
@@ -136,7 +136,7 @@
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void output_select(unsigned char cos);
+    void OutputSelect(unsigned char cos);
 
     /** Connect the comparator Output Pin to an external pin
     * @param input NC   disconnect CMPO from the associated CMPO output pin.
@@ -144,9 +144,9 @@
     * @param input PTC5 connect CMPO to PTC5.
     * @param input PTE0 connect CMPO to PTE0.
     * @param . Only one pin can be connected at any time.
-    * @param . Each time this function is called, the last pin will be disabled before the new pin is enabled
+    * @param . Each time this function is called, the last active pin will be disabled before the new pin is enabled
     */
-    void output_pin_en(PinName ope);
+    void OutputPin(PinName ope);
 
     /** Comparator Module Enable
     * @param . Enables the Analog Comparator module. When the module is not enabled,
@@ -166,7 +166,7 @@
     * @param input Unsigned char - range : 0..255
     * @return none
     */
-    void filter_period(unsigned char fipe);
+    void FilterPeriod(unsigned char fipe);
 
     /** DMA Enable Control
     * @param . Enables the DMA transfer triggered from the CMP module. When this field is set,
@@ -176,7 +176,7 @@
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void dma_en(unsigned char dmaen);
+    void dma(unsigned char dmaen);
 
     /** Analog Comparator Output
     * @param none
@@ -187,14 +187,14 @@
     */
     unsigned char status(void);
 
-    /** DAC Enable
+    /** DAC Enable Control
     * @param . Enables the DAC. When the DAC is disabled, it is powered down to conserve power.
     * @param . 0 DAC is disabled.
     * @param . 1 DAC is enabled.
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void dac_en(unsigned char den);
+    void dac(unsigned char den);
 
     /** Supply Voltage Reference Source Select
     * @param . 0 - V is selected as resistor ladder network supply reference Vin1 = VREFH
@@ -203,7 +203,7 @@
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void ref_source(unsigned char res);
+    void RefSource(unsigned char res);
 
     /** Set the detection threshold level - DAC Output Voltage Select
     * @param input float - range 0.0 .. 1.0
@@ -222,7 +222,7 @@
     * @param input Unsigned char - 0 or 1
     * @return none
     */
-    void pass_through(unsigned char ptm);
+    void PassThrough(unsigned char ptm);
 
     /** Plus Input Mux Control
     * @param . Determines which input is selected for the plus input of the comparator.
@@ -244,7 +244,7 @@
     * @param input Unsigned char - range 0..7
     * @return none
     */
-    void switch_plus(unsigned char pinP);
+    void SwitchPlus(unsigned char pinP);
 
     /** Minus Input Mux Control
     * @param . Determines which input is selected for the plus input of the comparator.
@@ -266,19 +266,13 @@
     * @param input Unsigned char - range 0..7
     * @return none
     */
-    void switch_min(unsigned char pinM);
-
-    /** Comparator enable/disable Interrupt
-    * @param 1 Enables the comparator ISR
-    * @param 0 Disabled the comparator ISR.
-    * @return none
-    */
-    void int_en(bool ien);
+    void SwitchMin(unsigned char pinM);
 
     /**
     * Comparator rising interrupt callback
     *
     * @param pointer to the user function to execute after IRQ assertion
+    * @param NULL to disable the interrupt
     * @return none
     */
     void rising(void(*fptr)(void));
@@ -287,6 +281,7 @@
     * Comparator falling interrupt callback
     *
     * @param pointer to the user function to execute after IRQ assertion
+    * @param NULL to disable the interrupt
     * @return none
     */
     void falling(void(*fptr)(void));

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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.h

Repository toolbox

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