led blinking

vineet kumar

Other Parts Discussed in Thread: PCF8575

I am presently working on 816x/389x spectral digital board from ti . I want to blink the led through sysfs enteries but i am unable to do it. i went through the schematic diagram and i found that the led are interface to P4,P5,P6 AND P7 PIN of PCF8575 I/O EXpander. The PCF8575 is intern interface with the MSP430 through i2c.

My doubt is whether i have to program the MSP430 for blinking the led or not . if the MSP430 is required to program than Please suggest me the way to do so

please help me out

over 12 years ago

0 Deepu Raj over 12 years ago

TI__Intellectual 925 points

vineet kumar,

You can blink the LED using the the i2c commands. The LEDs are connected using the PCF8575 I/O Expander. The I2C address of the IO Expander is 0x20 on the TI81XX EVM.

Please try the following command to test the LEDs

# i2cset 1 0x20 0x0 0xff

Please check the schematic for more detailed connection details

Regards,

-Deepu Raj- | Verify the Answer | if this post solved your issue

0 vineet kumar over 12 years ago in reply to Deepu Raj

Intellectual 730 points

Hi Deepu Raj

i2cset 1 0x20 0x0 0xff

would u please tell me more about this instruction and also where do i find all the related instruction so that i can check all the peripheral present on board.

0 Deepu Raj over 12 years ago in reply to vineet kumar

TI__Intellectual 925 points

vineet kumar,

The above command is used for writing a value to a particular I2C client address. The parameter details can be find by entering the "i2cset" command.

Example

# i2cset
Usage: i2cset [-f] [-y] [-m MASK] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE] [MODE]
I2CBUS is an integer or an I2C bus name
ADDRESS is an integer (0x03 - 0x77)
MODE is one of:
    c (byte, no value)
    b (byte data, default)
    w (word data)
    Append p for SMBus PEC

The "examples" folder present under the PSP release source code can be used for testing different modules.

-Deepu Raj-
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0 vineet kumar over 12 years ago in reply to Deepu Raj

Intellectual 730 points

Hi Deepu Raj

i have tried the above instruction and it is working fine for me . thanks for that . while executing instruction i can make out that we are doing or writing on /dev/i2c-1 file.

so i thought of opening this file through an user space application and program the led for blinking after regular interval. i am able to open the file without any error but I am

stuck in the next step i.e how to write to the pcf8575 through the application .

Please help me out

0 Deepu Raj over 12 years ago in reply to vineet kumar

TI__Intellectual 925 points

Vineeth Kumar,

You can use the linux user sapce i2c api for archiving the same.

Please find the bellow sample code snippet for the same

#include<stdio.h>
#include <fcntl.h>
#include "i2c-dev.h"

#define ADDRESS 0x20
#define I2C_DEV "/dev/i2c-1"

int main(){

        int fd;
        fd = open( I2C_DEV, O_RDWR );

        if( ioctl( fd, I2C_SLAVE, ADDRESS ) < 0 )
        {
                fprintf( stderr, "Failed to set slave address: %m\n" );
                return 2;
        }

        /* Try some i2c write */
        if(i2c_smbus_write_word_data(fd,0x0,0xff) < 0 )
                fprintf( stderr, "Failed to write to I2C device: %m\n" );

        printf(" I2C wite complere \n");

        return 0;
}

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