Porting DMA DAC example to LPC17X8

christian_oster — Mon, 10 Jul 2017 09:25:07 GMT

Hello,

i would like to port the example mentioned in AN10917 to a LPC1788 controller.

According to the UM10470 there is no PLCC-Register in LPC1788's PLL0CON register...

This is the original code from the Application Note

void InitClock(void)
{
// 1. Init OSC
SCS_bit.OSCRANGE = 0;
SCS_bit.OSCEN = 1;
// 2. Wait for OSC ready
while(!SCS_bit.OSCSTAT);
// 3. Disconnect PLL
PLL0CON_bit.PLLC = 0;
PLL0FEED = 0xAA;
PLL0FEED = 0x55;
// 4. Disable PLL
PLL0CON_bit.PLLE = 0;
PLL0FEED = 0xAA;
PLL0FEED = 0x55;
// 5. Select source clock for PLL
CLKSRCSEL_bit.CLKSRC = 1; // Selects the main oscillator as a PLL clock source.
// 6. Set PLL settings 300 MHz
PLL0CFG_bit.MSEL = 25-1;
PLL0CFG_bit.NSEL = 2-1;
PLL0FEED = 0xAA;
PLL0FEED = 0x55;
// 7. Enable PLL
PLL0CON_bit.PLLE = 1;
PLL0FEED = 0xAA;
PLL0FEED = 0x55;
// 8. Wait for the PLL to achieve lock
while(!PLL0STAT_bit.PLOCK);
// 9. Set clk divider settings
CCLKCFG = 3-1; // 1/3 Fpll
PCLKSEL0 = PCLKSEL1 = 0; // other peripherals 100/4 = 25MHz
// 10. Connect the PLL
PLL0CON_bit.PLLC = 1;
PLL0FEED = 0xAA;
PLL0FEED = 0x55;
}

And this is my try of porting it:

void InitClock(void)
{
// 1. Init OSC
   LPC_SC->SCS &= ~(1 << 4);//OSCRANGE
    LPC_SC->SCS |= (1 << 5); //OSCEN

// 2. Wait for OSC ready
while(!(LPC_SC->SCS & (1 << 6))); //OSCSTAT
// 3. Disconnect PLL
LPC_SC->PLL0CON &= ~(1 << 0);
LPC_SC->PLL0FEED = 0xAA;
LPC_SC->PLL0FEED = 0x55;
// 4. Disable PLL
LPC_SC->PLL0CON &= ~(1 << 0);
LPC_SC->PLL0FEED = 0xAA;
LPC_SC->PLL0FEED = 0x55;
// 5. Select source clock for PLL
LPC_SC->CLKSRCSEL |= 1; // Selects the main oscillator as a PLL clock source.
// 6. Set PLL settings 300 MHz
LPC_SC->PLL0CFG = 0x38;
LPC_SC->PLL0FEED = 0xAA;
LPC_SC->PLL0FEED = 0x55;
// 7. Enable PLL
LPC_SC->PLL0CON |= 1;
LPC_SC->PLL0FEED = 0xAA;
    LPC_SC->PLL0FEED = 0x55;
// 8. Wait for the PLL to achieve lock
    while(!(LPC_SC->PLL0STAT & (1 << 10)))
// 9. Set clk divider settings
LPC_SC->CCLKSEL |=   0x02;            // 1/3 Fpll
LPC_SC->PCLKSEL = 0x04;    // other peripherals 100/4 = 25MHz
// 10. Connect the PLL
LPC_SC->PLL0CON |= 1;
LPC_SC->PLL0FEED = 0xAA;
    LPC_SC->PLL0FEED = 0x55;
}

Can you tell me what changes i need to do, in order to use the example on the LPC1778/1788 ?

Thanks,

Christian

Re: Porting DMA DAC example to LPC17X8

jeremyzhou — Tue, 11 Jul 2017 02:32:18 GMT

Hi Christian Ostermeier ,

Thank you for your interest in NXP Semiconductor products and

for the opportunity to serve you.

About the clock initialize implementation of the LPC1788, you can refer to the LPCOpen libarary for details.

LPCOpen Software for LPC17XX|NXP

Have a great day,

TIC

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Porting DMA DAC example to LPC17X8

Re: Porting DMA DAC example to LPC17X8