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TLC5973: SDI pin

Eng Lih Khaw
Expert 2000 points
Part Number: TLC5973

Hi,

I've questions regarding TLC5973

- Can I use GPIO from microcontroller to drive the SDI pin? If no, please advise the appropriate pin to drive it

- Does this device has EVM?

Thanks

  • 0
    TI__Expert 3190 points

    Hi Lih,

    Yes, it depends on the data you transmitting. If the data is not too many, you can use GPIO to transmit.

    Regards,

    Shawn.

  • 0 in reply to Shawn Ding
    Expert 2000 points
    Hi Shawn,

    How to quantify the data is too many? I use this LED driver for dimming, flashing and change color purpose only.
    Please advise if it's feasible?

    Thanks!
  • 0 in reply to Eng Lih Khaw
    TI__Expert 3190 points

    Hi,

    If you cascade too many devices, the data will too many to transmit.

    Also if you MCU GPIO frequency is too small, it still effect the data transmitting speed.

    Regards,

    Shawn.

  • 0 in reply to Shawn Ding
    Expert 2000 points
    Hi Shawn,

    Thank you so much for your advise. I only use 1pcs of TLC5973. Cascading is not required.

    Btw, can this device do dimming, flashing and change color? I'm rather new to the 'single-wire' interface. Do you have the sample code on how to control it?

    Thanks
  • 0 in reply to Eng Lih Khaw
    TI__Expert 3190 points

    below code based on MSP432E401 for your reference, thanks.

    #define WRTCMD 0x3AA
    #define cascade_N 2

    int main(void)
    {
        uint8_t jj;
        uint64_t ii;
        uint64_t GSOUT0[cascade_N]={0x0FA};//GS data//data from IC1 to IC_N
        uint64_t GSOUT1[cascade_N]={0xF0F};
        uint64_t GSOUT2[cascade_N]={0xFFF};

        uint64_t Data;

        uint32_t systemClock;

        /* Configure the system clock for 120 MHz */
        systemClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
                                              SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480),
                                              120000000);
        /* Enable the clock to the GPIO Port A and wait for it to be ready */
         MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
         while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOA)))
         {

         }

        MAP_GPIOPinTypeGPIOOutput(GPIO_PORTA_BASE,GPIO_PIN_2);//set a wire as the output of one-wire,SDI

        //data transfer rate measurement, setup tcycle=48 system time. // rate 500kHz
        MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,4);//write 1
        MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
        MAP_SysCtlDelay(240);//2us
        MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,4);//write 1
        MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
        //data write
        while(1)
        {
    //      GPIODirModeSet(,GPIO_PIN_2,GPIO_DIR_MODE_OUT);//set a wire as the output of one-wire,SDI
            for(jj=1;jj<cascade_N;jj++)//N-1 cascaded device data
            {
                Data=(((uint64_t)WRTCMD)<<12)+GSOUT2[jj-1];
                Data=(Data<<12)+GSOUT1[jj-1];
                Data=(Data<<12)+GSOUT0[jj-1];
                for(ii=48;ii>0;ii--)//write Data
                {
                    MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,4);//write 1
                    MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
                    MAP_SysCtlDelay(60);//<50%
                    MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,Data>>(ii-3));//write data
                    MAP_SysCtlDelay(160);
                    MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
                }
                MAP_SysCtlDelay(960);//wait for 4.5 tcycle to generate EOS
            }

            Data=(((uint64_t)WRTCMD)<<12)+GSOUT2[cascade_N-1];
            Data=(Data<<12)+GSOUT1[cascade_N-1];
            Data=(Data<<12)+GSOUT0[cascade_N-1];
            for(ii=48;ii>0;ii--)//write Data// last one data
            {
                MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,4);//write 1
                MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
                MAP_SysCtlDelay(60);//<50%
                MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,Data>>(ii-3));//write data
                MAP_SysCtlDelay(160);
                MAP_GPIOPinWrite(GPIO_PORTA_BASE,GPIO_PIN_2,0);//write 0
            }
            MAP_SysCtlDelay(2400);//LAT generated,>8 tclock

        }
    }