/*
Taktgenerator fuer RP2040 Pico Pi mit Ausgang an GPIO21.

2025-07-21
Michael Nowak
www.mino-elektronik.de
*/

#include"rp2040_arduino.h"          // Registerdefinitionen
#define BIT(x) (1<<x)

#define DEF_SYSCLOCK  250000000   // default
#define MHZ_12         12000000   // default

#define MHZ_FAKTOR      1000000   // 1e6

#define REF_DIV     2
#define PLL_DIV1    3             //
#define PLL_DIV2    2             // 

void kurz_warten(void)    // fuer kurze Verzoegerungen
{
  volatile int i = 10000;
  while(i--);
}  


void setup() {
  // put your setup code here, to run once:
  VREG_AND_CHIP_RESET_SET-> VREG = 15<<VREG_AND_CHIP_RESET_VREG_VSEL_Pos;
  while(!(VREG_AND_CHIP_RESET->VREG & VREG_AND_CHIP_RESET_VREG_ROK_Msk));
  kurz_warten();       // Vreg abwarten

  XOSC->CTRL     = (XOSC_CTRL_FREQ_RANGE_1_15MHZ << XOSC_CTRL_FREQ_RANGE_Pos);
  XOSC->STARTUP  = 100;             // ca. 2 ms bei 12 MHz
  XOSC_SET->CTRL = (XOSC_CTRL_ENABLE_ENABLE << XOSC_CTRL_ENABLE_Pos);
  while (!(XOSC->STATUS & XOSC_STATUS_STABLE_Msk));
  
  RESETS_CLR->RESET = RESETS_RESET_pll_sys_Msk;
  while (!(RESETS->RESET_DONE & RESETS_RESET_pll_sys_Msk));

  PLL_SYS->PRIM = (PLL_DIV1 << PLL_SYS_PRIM_POSTDIV1_Pos) |   // postdivider auf /6 einstellen
                  (PLL_DIV2 << PLL_SYS_PRIM_POSTDIV2_Pos);
  PLL_SYS->CS = (REF_DIV << PLL_SYS_CS_REFDIV_Pos);           // PLL-Aufloesung 6 MHz
  PLL_SYS->FBDIV_INT = (DEF_SYSCLOCK*PLL_DIV2*REF_DIV)/(MHZ_12/PLL_DIV1);  // Sollfrequenz
   PLL_SYS_CLR->PWR = PLL_SYS_PWR_VCOPD_Msk | PLL_SYS_PWR_PD_Msk;
  while (!(PLL_SYS->CS & PLL_SYS_CS_LOCK_Msk));

  PLL_SYS_CLR->PWR = PLL_SYS_PWR_POSTDIVPD_Msk;

  CLOCKS->CLK_REF_CTRL = (CLOCKS_CLK_REF_CTRL_SRC_xosc_clksrc << CLOCKS_CLK_REF_CTRL_SRC_Pos);
  CLOCKS->CLK_SYS_CTRL = (CLOCKS_CLK_SYS_CTRL_AUXSRC_clksrc_pll_sys << CLOCKS_CLK_SYS_CTRL_AUXSRC_Pos);
  CLOCKS_SET->CLK_SYS_CTRL = (CLOCKS_CLK_SYS_CTRL_SRC_clksrc_clk_sys_aux << CLOCKS_CLK_SYS_CTRL_SRC_Pos);

  CLOCKS->CLK_PERI_CTRL = CLOCKS_CLK_PERI_CTRL_ENABLE_Msk |
      (CLOCKS_CLK_PERI_CTRL_AUXSRC_clk_sys << CLOCKS_CLK_PERI_CTRL_AUXSRC_Pos);

  CLOCKS->CLK_ADC_CTRL = CLOCKS_CLK_ADC_CTRL_ENABLE_Msk |
      (CLOCKS_CLK_ADC_CTRL_AUXSRC_xosc_clksrc << CLOCKS_CLK_ADC_CTRL_AUXSRC_Pos);

// enable GPIO
  RESETS_CLR->RESET = RESETS_RESET_io_bank0_Msk | 
                      RESETS_RESET_pads_bank0_Msk;
  while((RESETS->RESET_DONE & (RESETS_RESET_io_bank0_Msk | RESETS_RESET_pads_bank0_Msk)) !=
        (RESETS_RESET_io_bank0_Msk | RESETS_RESET_pads_bank0_Msk));

  CLOCKS->CLK_GPOUT0_CTRL = CLOCKS_CLK_GPOUT0_CTRL_ENABLE_Msk |         // enable
                            6 << CLOCKS_CLK_GPOUT0_CTRL_AUXSRC_Pos;     // pll_sys als Quelle
  IO_BANK0->GPIO21_CTRL = IO_BANK0_GPIO21_CTRL_FUNCSEL_clocks_gpout_0;  // fester Ausgang
  PADS_BANK0->GPIO21 |= 3<<PADS_BANK0_GPIO21_DRIVE_Pos |                // hoher Ausgangsstrom
                        PADS_BANK0_GPIO21_SLEWFAST_Msk;                 // und schnelle Anstiegszeit - sofern notwendig
  SIO->GPIO_OE_SET = BIT(21);                                           // Ausgang freigeben

}

void loop() {
  // put your main code here, to run repeatedly:

}