cancel
Showing results for 
Search instead for 
Did you mean: 

PSoC™ 4

Marcus_Hellen
New Contributor II

Hello Everyone,

I am using cy8ckit-041-41xx Psoc 4S- Series Pioneer kit. I want to change led brightness via pwm. I am sharing my Topdesign and code. My goal is when I touch my touchpad over on X coordinate led brightness should change. For example, when X coordinate equal to 0, Led brightness sould be lower. When X coordinate equal to 100, Led brightness sould be highest. 

 

First thing which comes to my mind is : 

Xcord = CapSense_GetXYCoordinates(CapSense_TOUCHPAD_WDGT_ID);
Ycord = Xcord >>16;
Xcord = (uint16)Xcord;

PWM_WritePeriod(100* Xcord);
LED2_Write(LED_ON); 

but it did not work. 

Could you help me please?

Marcus

0 Likes
1 Solution
MotooTanaka
Esteemed Contributor

Hi,

 

In recent PSoC Creator GUI, we can not set compare value to period value, 

but to realize duty = 100%, we need to set compare value to period value (or greater).

Meantime, to realize duty = 0%, we need to set compare value to 0.

And these can be done within the software.

 

So I hacked the following test program with CY8CKIT-149 (CY8C4147AZI-S475)

Note: For your board, please change the target device to your device and change pins to fit your board.

 

When built and run, the serial output to Tera Term was something like

001-TeraTerm-log.JPG

When I entered "compare 0" the LED was total off (duty = 0%).

When I entered "compare 9999", which is period == compare,

and the LED was the brightest (duty = 100%)

When I entered "compare 10000", which is period < compare,

but program and PWM component accepted the value, but the brightness did not increase.

When I entered "compare 4999", which is period == 2 * compare, and LED was about half bright.

 

Followings are the brief of the project

Note: As usual, I cheated with using my tty_utils.

Schematic

002-schematic.JPG

Pins

003-Pins.JPG

main.c

#include "project.h"
#include "stdio.h"
#include "tty_utils.h"

char    cmd[STR_BUF_LEN+1] ;

void init_hardware(void)
{
    CyGlobalIntEnable; /* Enable global interrupts. */
    tty_init() ;
    PWM_Start() ;
}

void help(void)
{
    print("=== Usage ===\n\r") ;
    print("period  <value> : set PWM period to  <value>\n\r") ;
    print("compare <value> : set PWM compare to <value>\n\r") ;
    print("status          : print PWM status\n\r") ;
    print("help            : print this usage\n\r") ;
    print("=============\r\n") ;
}

void status_report(void)
{
    uint16_t period, compare ;
    period = PWM_ReadPeriod() ;
    compare = PWM_ReadCompare() ;
    snprintf(str, STR_BUF_LEN,
        "PWM: Period: %hu,  Compare: %hu\n\r",
        period, compare) ;
    print(str) ;
}

void set_pwm_period(uint16_t period)
{
    PWM_Stop() ;
    PWM_WritePeriod(period) ;
    PWM_WriteCounter(0) ;
    PWM_Enable() ;
    status_report() ;
}

void set_pwm_compare(uint16_t compare) 
{
    // PWM_Stop() // for compare PWM can be running
    PWM_WriteCompare(compare) ;
    PWM_WriteCounter(0) ; // When counter == 0 compare value gets updated
    // PWM_Enable() // for compare PWM can be running
    status_report() ;
}

int main(void)
{
    uint16_t period, compare ;
    
    init_hardware() ;
    
    period = PWM_ReadPeriod() ;
    compare = PWM_ReadCompare() ;
    
    splash("PWM TEST") ;
    help() ;
    status_report() ;
    
    prompt() ;

    for(;;) {
        if (get_line()) {
            sscanf(str, "%s", cmd) ;
            switch(cmd[0]) {
            case 'p': case 'P': // period
                sscanf(str, "%*s %hu", &period)  ;
                set_pwm_period(period) ;
                break ;
            case 'c': case 'C': // compare
                sscanf(str, "%*s %hu", &compare) ;
                set_pwm_compare(compare) ;
                break ;
            case 's': case 'S': // status report
                status_report() ;
                break ;
            default: 
                help() ;
                break ;
            }
            prompt() ;
        }
    }
}

 

moto

View solution in original post

3 Replies
Bob_Marlowe
Expert II

 To change LED brightness with a PWM you should keep the period constant (resulting in something like 100 to 1000 Hz) and change the compare value between 1 and period value -1.

 

Happy coding

Bob

 

 

 

Len_CONSULTRON
Honored Contributor II

Marcus,

Change your code to:

Xcord = CapSense_GetXYCoordinates(CapSense_TOUCHPAD_WDGT_ID);
Ycord = Xcord >>16;
Xcord = (uint16)Xcord;

PWM_WriteCompare(100* Xcord);
LED2_Write(LED_ON); 

Give it a try.

Changing the duty cycle is more what you want to do as Bob indicated.

Len
"Engineering is an Art. The Art of Compromise."
MotooTanaka
Esteemed Contributor

Hi,

 

In recent PSoC Creator GUI, we can not set compare value to period value, 

but to realize duty = 100%, we need to set compare value to period value (or greater).

Meantime, to realize duty = 0%, we need to set compare value to 0.

And these can be done within the software.

 

So I hacked the following test program with CY8CKIT-149 (CY8C4147AZI-S475)

Note: For your board, please change the target device to your device and change pins to fit your board.

 

When built and run, the serial output to Tera Term was something like

001-TeraTerm-log.JPG

When I entered "compare 0" the LED was total off (duty = 0%).

When I entered "compare 9999", which is period == compare,

and the LED was the brightest (duty = 100%)

When I entered "compare 10000", which is period < compare,

but program and PWM component accepted the value, but the brightness did not increase.

When I entered "compare 4999", which is period == 2 * compare, and LED was about half bright.

 

Followings are the brief of the project

Note: As usual, I cheated with using my tty_utils.

Schematic

002-schematic.JPG

Pins

003-Pins.JPG

main.c

#include "project.h"
#include "stdio.h"
#include "tty_utils.h"

char    cmd[STR_BUF_LEN+1] ;

void init_hardware(void)
{
    CyGlobalIntEnable; /* Enable global interrupts. */
    tty_init() ;
    PWM_Start() ;
}

void help(void)
{
    print("=== Usage ===\n\r") ;
    print("period  <value> : set PWM period to  <value>\n\r") ;
    print("compare <value> : set PWM compare to <value>\n\r") ;
    print("status          : print PWM status\n\r") ;
    print("help            : print this usage\n\r") ;
    print("=============\r\n") ;
}

void status_report(void)
{
    uint16_t period, compare ;
    period = PWM_ReadPeriod() ;
    compare = PWM_ReadCompare() ;
    snprintf(str, STR_BUF_LEN,
        "PWM: Period: %hu,  Compare: %hu\n\r",
        period, compare) ;
    print(str) ;
}

void set_pwm_period(uint16_t period)
{
    PWM_Stop() ;
    PWM_WritePeriod(period) ;
    PWM_WriteCounter(0) ;
    PWM_Enable() ;
    status_report() ;
}

void set_pwm_compare(uint16_t compare) 
{
    // PWM_Stop() // for compare PWM can be running
    PWM_WriteCompare(compare) ;
    PWM_WriteCounter(0) ; // When counter == 0 compare value gets updated
    // PWM_Enable() // for compare PWM can be running
    status_report() ;
}

int main(void)
{
    uint16_t period, compare ;
    
    init_hardware() ;
    
    period = PWM_ReadPeriod() ;
    compare = PWM_ReadCompare() ;
    
    splash("PWM TEST") ;
    help() ;
    status_report() ;
    
    prompt() ;

    for(;;) {
        if (get_line()) {
            sscanf(str, "%s", cmd) ;
            switch(cmd[0]) {
            case 'p': case 'P': // period
                sscanf(str, "%*s %hu", &period)  ;
                set_pwm_period(period) ;
                break ;
            case 'c': case 'C': // compare
                sscanf(str, "%*s %hu", &compare) ;
                set_pwm_compare(compare) ;
                break ;
            case 's': case 'S': // status report
                status_report() ;
                break ;
            default: 
                help() ;
                break ;
            }
            prompt() ;
        }
    }
}

 

moto

View solution in original post