Need help trying to interface to STP1612PW05 LED driver

# 27 Jan 2012

Hi there,

I am trying to interface to this 16 bit LED driver from ST ( http://www.st.com/internet/analog/product/215262.jsp ). It interfaces via SPI but the problem is that to send configuration data to it I need to have one of its pins high for a certain number of bits (yes, bits...). I am not sure how to do that with the current SPI library and I can't seem to find another way. Please refer to page 14 of the data sheet ( http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00237442.pdf ) to gain further understanding of what I mean... Any insight on this would be greatly appreciated.

Regards, Kartik

ceri clatworthy

# 27 Jan 2012

If config is a one off, then I'd bit bash SPI For that frame, But if it is more frequent, then I think you can actuality Have a FOUR bit SPI frame ?

So you would send 4 bit frame, toggle pin, send 12 bit frame.

Will look at data sheet a little later, just to make sure.

Ceri

ceri clatworthy

# 27 Jan 2012

If it is fig. 7, then. This is 16 bit packets, Therefore, a pulse afterwards should be OK. Have a look for TLC9540, In the cool book ? It is amazingly similar.

Ceri

Kartik Jangam

# 27 Jan 2012

You mean the TLC5940? I did but its only 12 bit. I am using this to drive servos. Ok, so a 4 bit packet should work, how do I know that the SPI library sends the most significant bit first? Also which "mode" of SPI do I need to use with this? My guess is "mode 0"...

Thanks again for taking the time to help me.

Regards, Kartik

Kartik Jangam

# 27 Jan 2012

Ceri, What do you mean by bit bashing the SPI? Yes the configuration is a one off thing in the beginning of the program. Although in the data sheet fig. 6 shows that the LE needs to go high at the 6th or 7th bit all the way to the 16th bit then low.

ceri clatworthy

# 27 Jan 2012

CS = 0
Data = 1
Clock = 1
Clock = 0
 ....
....
.....
....
Le = 1
Data ...
Clock...
Clock
.....
....
....
....
Le = 0
Ce = 1

You simply toggle the bits manual, You could put it in a loop, in a subroutine.

Kartik Jangam

# 27 Jan 2012

So this is what I did and still a no go.

#include "mbed.h"


PwmOut pwclk (p21);
DigitalOut mosi (p5);
DigitalOut le (p6);
DigitalOut clk (p7);
unsigned short servo_pos [16] = {0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF};
unsigned short config = 0xFAAF;

void servo_init (unsigned short config);
void servo_write (unsigned short servo_pos []);

int main()
{
    le = 0;
    clk = 0;
    mosi = 0;
     
    LPC_PWM1->TCR = (1 << 1);               // Reset counter, disable PWM
    LPC_SC->PCLKSEL0 &= ~(0x3 << 12);  
    LPC_SC->PCLKSEL0 |= (1 << 12);          // Set peripheral clock divider to /1, i.e. system clock
    LPC_PWM1->MR0 = 29;                     // Match Register 0 is shared period counter for all PWM1
    LPC_PWM1->MR6 = 14;                      // Pin 21 is PWM output 6, so Match Register 6
    LPC_PWM1->LER |= 1;                     // Start updating at next period start
    LPC_PWM1->TCR = (1 << 0) || (1 << 3);   // Enable counter and PWM
    
    servo_init (config);
    
    while (1)
    {
        servo_write (servo_pos);
    }
}

void servo_init (unsigned short config)
{
    clk = 0;
    for (int i = 0; i < 16; i++)
    {
        clk = 0;
        if (i >= 6 && i < 16)
            le = 1;
        else
            le = 0;
        
        if (config & 0x8000)
            mosi = 1;
        else
            mosi = 0;
        config = config << 1;
        clk = 1;
    }
    le = 0;
}

void servo_write (unsigned short servo_pos [])
{
    unsigned int byte = 0;
    le = 0;
    clk = 0;
    for (int k = 15; k >= 0; k--)
    {
        byte = servo_pos [k];
        for (int i = 0; i < 16; i++)
        {
            clk = 0;
            if (byte & 0x8000)
                mosi = 1;
            else
                mosi = 0;
            byte = byte << 1;
            clk = 1;
        }
    }
    le = 1;
    le = 0;
}

So this is what I did and still a no go. <<code>> #include "mbed.h" PwmOut pwclk (p21); DigitalOut mosi (p5); DigitalOut le (p6); DigitalOut clk (p7); unsigned short servo_pos [16] = {0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF}; unsigned short config = 0xFAAF; void servo_init (unsigned short config); void servo_write (unsigned short servo_pos []); int main() { le = 0; clk = 0; mosi = 0; LPC_PWM1->TCR = (1 << 1); // Reset counter, disable PWM LPC_SC->PCLKSEL0 &= ~(0x3 << 12); LPC_SC->PCLKSEL0 |= (1 << 12); // Set peripheral clock divider to /1, i.e. system clock LPC_PWM1->MR0 = 29; // Match Register 0 is shared period counter for all PWM1 LPC_PWM1->MR6 = 14; // Pin 21 is PWM output 6, so Match Register 6 LPC_PWM1->LER |= 1; // Start updating at next period start LPC_PWM1->TCR = (1 << 0) || (1 << 3); // Enable counter and PWM servo_init (config); while (1) { servo_write (servo_pos); } } void servo_init (unsigned short config) { clk = 0; for (int i = 0; i < 16; i++) { clk = 0; if (i >= 6 && i < 16) le = 1; else le = 0; if (config & 0x8000) mosi = 1; else mosi = 0; config = config << 1; clk = 1; } le = 0; } void servo_write (unsigned short servo_pos []) { unsigned int byte = 0; le = 0; clk = 0; for (int k = 15; k >= 0; k--) { byte = servo_pos [k]; for (int i = 0; i < 16; i++) { clk = 0; if (byte & 0x8000) mosi = 1; else mosi = 0; byte = byte << 1; clk = 1; } } le = 1; le = 0; } <</code>>

Kartik Jangam

# 28 Jan 2012

Alright... everything is solved and working correctly. Thanks for your help!

#include "mbed.h"


PwmOut pwclk (p21);
DigitalOut mosi (p5);
DigitalOut le (p6);
DigitalOut clk (p7);
unsigned short servo_pos [16] = {60620, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF};
unsigned short config = 0xFAAF;

void servo_init (unsigned short config);
void servo_write (unsigned short servo_pos []);

int main()
{
    le = 0;
    clk = 0;
    mosi = 0;
     
    LPC_PWM1->TCR = (1 << 1);               // Reset counter, disable PWM
    LPC_SC->PCLKSEL0 &= ~(0x3 << 12);  
    LPC_SC->PCLKSEL0 |= (1 << 12);          // Set peripheral clock divider to /1, i.e. system clock
    LPC_PWM1->MR0 = 29;                     // Match Register 0 is shared period counter for all PWM1
    LPC_PWM1->MR6 = 14;                      // Pin 21 is PWM output 6, so Match Register 6
    LPC_PWM1->LER |= 1;                     // Start updating at next period start
    LPC_PWM1->TCR = (1 << 0) || (1 << 3);   // Enable counter and PWM
    
    servo_init (config);
    
    while (1)
    {
        servo_write (servo_pos);
    }
}

void servo_init (unsigned short config)
{
    clk = 0;
    for (int i = 0; i < 16; i++)
    {
        clk = 0;
        mosi = 0;
        if (i >= 5 && i < 16)
            le = 1;
        else
            le = 0;
        
        if (config & 0x8000)
            mosi = 1;
        else
            mosi = 0;
        config = config << 1;
        clk = 1;
    }
    mosi = 0;
    clk = 0;
    le = 0;
}

void servo_write (unsigned short servo_pos [])
{
    unsigned int byte = 0;
    le = 0;
    clk = 0;
    for (int k = 15; k >= 0; k--)
    {
        byte = servo_pos [k];
        for (int i = 0; i < 16; i++)
        {
            clk = 0;
            mosi = 0;
            if (k == 0 && i >= 13)
                le = 1;
            else
                le = 0;
            if (byte & 0x8000)
                mosi = 1;
            else
                mosi = 0;
            byte = byte << 1;
            
            clk = 1;            
        }
    }
    mosi = 0;
    clk = 0;
    le = 0;
}

Alright... everything is solved and working correctly. Thanks for your help! <<code>> #include "mbed.h" PwmOut pwclk (p21); DigitalOut mosi (p5); DigitalOut le (p6); DigitalOut clk (p7); unsigned short servo_pos [16] = {60620, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF}; unsigned short config = 0xFAAF; void servo_init (unsigned short config); void servo_write (unsigned short servo_pos []); int main() { le = 0; clk = 0; mosi = 0; LPC_PWM1->TCR = (1 << 1); // Reset counter, disable PWM LPC_SC->PCLKSEL0 &= ~(0x3 << 12); LPC_SC->PCLKSEL0 |= (1 << 12); // Set peripheral clock divider to /1, i.e. system clock LPC_PWM1->MR0 = 29; // Match Register 0 is shared period counter for all PWM1 LPC_PWM1->MR6 = 14; // Pin 21 is PWM output 6, so Match Register 6 LPC_PWM1->LER |= 1; // Start updating at next period start LPC_PWM1->TCR = (1 << 0) || (1 << 3); // Enable counter and PWM servo_init (config); while (1) { servo_write (servo_pos); } } void servo_init (unsigned short config) { clk = 0; for (int i = 0; i < 16; i++) { clk = 0; mosi = 0; if (i >= 5 && i < 16) le = 1; else le = 0; if (config & 0x8000) mosi = 1; else mosi = 0; config = config << 1; clk = 1; } mosi = 0; clk = 0; le = 0; } void servo_write (unsigned short servo_pos []) { unsigned int byte = 0; le = 0; clk = 0; for (int k = 15; k >= 0; k--) { byte = servo_pos [k]; for (int i = 0; i < 16; i++) { clk = 0; mosi = 0; if (k == 0 && i >= 13) le = 1; else le = 0; if (byte & 0x8000) mosi = 1; else mosi = 0; byte = byte << 1; clk = 1; } } mosi = 0; clk = 0; le = 0; } <</code>>

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