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- /* ___DISCLAIMER___ */
- /* clock.c: PLL, CCLK, PCLK controls */
- #include <arm/NXP/LPC17xx/LPC17xx.h>
- #include "clock.h"
- #include "bits.h"
- #include "uart.h"
- void clock_disconnect() {
- disconnectPLL0();
- disablePLL0();
- }
- void clock_init() {
- /* set flash access time to 5 clks (80<f<=100MHz) */
- setFlashAccessTime(5);
- /* setup PLL0 for ~44100*256*8 Hz
- Base clock: 12MHz
- Multiplier: 429
- Pre-Divisor: 19
- Divisor: 6
- (want: 90316800, get: 90315789.47)
- -> DAC freq = 44099.5 Hz
- -> FPGA freq = 11289473.7Hz
- First, disable and disconnect PLL0.
- */
- // clock_disconnect();
- /* PLL is disabled and disconnected. setup PCLK NOW as it cannot be changed
- reliably with PLL0 connected.
- see:
- http://ics.nxp.com/support/documents/microcontrollers/pdf/errata.lpc1754.pdf
- */
- /* continue with PLL0 setup:
- enable the xtal oscillator and wait for it to become stable
- set the oscillator as clk source for PLL0
- set PLL0 multiplier+predivider
- enable PLL0
- set CCLK divider
- wait for PLL0 to lock
- connect PLL0
- done
- */
- enableMainOsc();
- setClkSrc(CLKSRC_MAINOSC);
- // XXX setPLL0MultPrediv(429, 19);
- // XXX setPLL0MultPrediv(23, 2);
- setPLL0MultPrediv(12, 1);
- enablePLL0();
- setCCLKDiv(3);
- connectPLL0();
- }
- void setFlashAccessTime(uint8_t clocks) {
- LPC_SC->FLASHCFG=FLASHTIM(clocks);
- }
- void setPLL0MultPrediv(uint16_t mult, uint8_t prediv) {
- LPC_SC->PLL0CFG=PLL_MULT(mult) | PLL_PREDIV(prediv);
- PLL0feed();
- }
- void enablePLL0() {
- LPC_SC->PLL0CON |= PLLE0;
- PLL0feed();
- }
- void disablePLL0() {
- LPC_SC->PLL0CON &= ~PLLE0;
- PLL0feed();
- }
- void connectPLL0() {
- while(!(LPC_SC->PLL0STAT&PLOCK0));
- LPC_SC->PLL0CON |= PLLC0;
- PLL0feed();
- }
- void disconnectPLL0() {
- LPC_SC->PLL0CON &= ~PLLC0;
- PLL0feed();
- }
- void setCCLKDiv(uint8_t div) {
- LPC_SC->CCLKCFG=CCLK_DIV(div);
- }
- void enableMainOsc() {
- LPC_SC->SCS=OSCEN;
- while(!(LPC_SC->SCS&OSCSTAT));
- }
- void disableMainOsc() {
- LPC_SC->SCS=0;
- }
- void PLL0feed() {
- LPC_SC->PLL0FEED=0xaa;
- LPC_SC->PLL0FEED=0x55;
- }
- void setClkSrc(uint8_t src) {
- LPC_SC->CLKSRCSEL=src;
- }
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