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https://github.com/licsber/micropython.git
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1c32cec7f1
The range is 1MHz - 48 MHz. Note that below 8 MHz there is no USB support. The frequency will be set to an integer fraction of 48 MHz. And after changing the frequency, the peripherals like PWM, UART, I2C, SPI have to be reconfigured. Current consumption e.g. of the Seeed Xiao board at 1 MHz is about 1.5 mA, mostly caused by the on-board LED (green LED with 1k resistor at 3.3V).
236 lines
9.1 KiB
C
236 lines
9.1 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* This file provides functions for configuring the clocks.
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2022 Robert Hammelrath
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdint.h>
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#include "py/runtime.h"
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#include "py/mphal.h"
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#include "samd_soc.h"
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static uint32_t cpu_freq = CPU_FREQ;
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static uint32_t peripheral_freq = DFLL48M_FREQ;
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static uint32_t dfll48m_calibration;
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int sercom_gclk_id[] = {
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GCLK_CLKCTRL_ID_SERCOM0_CORE, GCLK_CLKCTRL_ID_SERCOM1_CORE,
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GCLK_CLKCTRL_ID_SERCOM2_CORE, GCLK_CLKCTRL_ID_SERCOM3_CORE,
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GCLK_CLKCTRL_ID_SERCOM4_CORE, GCLK_CLKCTRL_ID_SERCOM5_CORE
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};
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uint32_t get_cpu_freq(void) {
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return cpu_freq;
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}
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uint32_t get_peripheral_freq(void) {
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return peripheral_freq;
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}
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void set_cpu_freq(uint32_t cpu_freq_arg) {
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// Set 1 waitstate to be safe
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NVMCTRL->CTRLB.reg = NVMCTRL_CTRLB_MANW | NVMCTRL_CTRLB_RWS(1);
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int div = DFLL48M_FREQ / cpu_freq_arg;
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peripheral_freq = cpu_freq = DFLL48M_FREQ / div;
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// Enable GCLK output: 48M on both CCLK0 and GCLK2
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(0) | GCLK_GENDIV_DIV(div);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(0);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(2) | GCLK_GENDIV_DIV(div);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(2);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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if (cpu_freq >= 8000000) {
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// Enable GCLK output: 48MHz on GCLK5 for USB
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(5) | GCLK_GENDIV_DIV(1);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(5);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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} else {
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// Disable GCLK output on GCLK5 for USB, since USB is not reliable below 8 Mhz.
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GCLK->GENCTRL.reg = GCLK_GENCTRL_ID(5);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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}
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// Set 0 waitstates for slower CPU clock
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NVMCTRL->CTRLB.reg = NVMCTRL_CTRLB_MANW | NVMCTRL_CTRLB_RWS(cpu_freq > 24000000 ? 1 : 0);
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}
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void check_usb_recovery_mode(void) {
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#if !MICROPY_HW_XOSC32K
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mp_hal_delay_ms(500);
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// Check USB status. If not connected, switch DFLL48M back to open loop
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if (USB->DEVICE.DeviceEndpoint[0].EPCFG.reg == 0) {
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// Set/keep the open loop mode of the device.
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SYSCTRL->DFLLVAL.reg = dfll48m_calibration;
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SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_CCDIS | SYSCTRL_DFLLCTRL_ENABLE;
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}
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#endif // MICROPY_HW_XOSC32K
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}
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void init_clocks(uint32_t cpu_freq) {
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dfll48m_calibration = 0; // please the compiler
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// SAMD21 Clock settings
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// GCLK0: 48MHz from DFLL open loop mode or closed loop mode from 32k Crystal
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// GCLK1: 32768 Hz from 32K ULP or DFLL48M
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// GCLK2: 48MHz from DFLL for Peripherals
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// GCLK3: 1Mhz for the us-counter (TC4/TC5)
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// GCLK4: 32kHz from crystal, if present
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// GCLK5: 48MHz from DFLL for USB
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// GCLK8: 1kHz clock for WDT
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NVMCTRL->CTRLB.bit.MANW = 1; // errata "Spurious Writes"
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NVMCTRL->CTRLB.bit.RWS = 1; // 1 read wait state for 48MHz
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#if MICROPY_HW_XOSC32K
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// Set up OSC32K according datasheet 17.6.3
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SYSCTRL->XOSC32K.reg = SYSCTRL_XOSC32K_STARTUP(0x3) | SYSCTRL_XOSC32K_EN32K |
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SYSCTRL_XOSC32K_XTALEN;
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SYSCTRL->XOSC32K.bit.ENABLE = 1;
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while (SYSCTRL->PCLKSR.bit.XOSC32KRDY == 0) {
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}
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// Set up the DFLL48 according to the data sheet 17.6.7.1.2
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// Step 1: Set up the reference clock
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#if MICROPY_HW_MCU_OSC32KULP
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// Connect the GCLK1 to the XOSC32KULP
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(1);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(1);
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#else
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// Connect the GCLK1 to OSC32K via GCLK1 to the DFLL input and for further use.
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(1);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(1);
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#endif
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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// Connect the GCLK4 to OSC32K via GCLK1 to the DFLL input and for further use.
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(4) | GCLK_GENDIV_DIV(1);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(4);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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// Connect GCLK4 to the DFLL input and for further use.
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID_DFLL48 | GCLK_CLKCTRL_GEN_GCLK4 | GCLK_CLKCTRL_CLKEN;
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// Enable access to the DFLLCTRL reg acc. to Errata 1.2.1
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SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_ENABLE;
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while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) {
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}
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// Step 2: Set the coarse and fine values.
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// Get the coarse value from the calib data. In case it is not set,
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// set a midrange value.
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uint32_t coarse = (*((uint32_t *)FUSES_DFLL48M_COARSE_CAL_ADDR) & FUSES_DFLL48M_COARSE_CAL_Msk)
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>> FUSES_DFLL48M_COARSE_CAL_Pos;
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if (coarse == 0x3f) {
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coarse = 0x1f;
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}
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SYSCTRL->DFLLVAL.reg = SYSCTRL_DFLLVAL_COARSE(coarse) | SYSCTRL_DFLLVAL_FINE(512);
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while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) {
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}
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// Step 3: Set the multiplication values. The offset of 16384 to the freq is for rounding.
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SYSCTRL->DFLLMUL.reg = SYSCTRL_DFLLMUL_MUL((CPU_FREQ + 16384) / 32768) |
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SYSCTRL_DFLLMUL_FSTEP(1) | SYSCTRL_DFLLMUL_CSTEP(1);
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while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) {
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}
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// Step 4: Start the DFLL and wait for the PLL lock. We just wait for the fine lock, since
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// coarse adjusting is bypassed.
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SYSCTRL->DFLLCTRL.reg |= SYSCTRL_DFLLCTRL_MODE | SYSCTRL_DFLLCTRL_WAITLOCK | SYSCTRL_DFLLCTRL_STABLE |
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SYSCTRL_DFLLCTRL_BPLCKC | SYSCTRL_DFLLCTRL_ENABLE;
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while (SYSCTRL->PCLKSR.bit.DFLLLCKF == 0) {
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}
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#else // MICROPY_HW_XOSC32K
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// Enable DFLL48M
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SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_ENABLE;
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while (!SYSCTRL->PCLKSR.bit.DFLLRDY) {
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}
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uint32_t coarse = (*((uint32_t *)FUSES_DFLL48M_COARSE_CAL_ADDR) & FUSES_DFLL48M_COARSE_CAL_Msk)
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>> FUSES_DFLL48M_COARSE_CAL_Pos;
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if (coarse == 0x3f) {
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coarse = 0x1f;
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}
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SYSCTRL->DFLLVAL.reg = SYSCTRL_DFLLVAL_COARSE(coarse) | SYSCTRL_DFLLVAL_FINE(511);
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#if MICROPY_HW_DFLL_USB_SYNC
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// Configure the DFLL48M for USB clock recovery.
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// Will have to switch back if no USB
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SYSCTRL->DFLLSYNC.bit.READREQ = 1;
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dfll48m_calibration = SYSCTRL->DFLLVAL.reg;
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// Set the Multiplication factor.
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SYSCTRL->DFLLMUL.reg = SYSCTRL_DFLLMUL_CSTEP(1) | SYSCTRL_DFLLMUL_FSTEP(1)
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| SYSCTRL_DFLLMUL_MUL(48000);
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// Set the mode to closed loop USB Recovery mode
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SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_USBCRM | SYSCTRL_DFLLCTRL_CCDIS
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| SYSCTRL_DFLLCTRL_MODE | SYSCTRL_DFLLCTRL_ENABLE;
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#else
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// Set/keep the open loop mode of the device.
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SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_CCDIS | SYSCTRL_DFLLCTRL_ENABLE;
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#endif
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while (!SYSCTRL->PCLKSR.bit.DFLLRDY) {
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}
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// Enable 32768 Hz on GCLK1 for consistency
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(48016384 / 32768);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(1);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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#endif // MICROPY_HW_XOSC32K
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set_cpu_freq(cpu_freq);
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// Enable GCLK output: 1MHz on GCLK3 for TC4
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(3) | GCLK_GENDIV_DIV(48);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(3);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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// Set GCLK8 to 1 kHz.
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GCLK->GENDIV.reg = GCLK_GENDIV_ID(8) | GCLK_GENDIV_DIV(32);
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GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(8);
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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}
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void enable_sercom_clock(int id) {
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// Enable synchronous clock. The bits are nicely arranged
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PM->APBCMASK.reg |= 0x04 << id;
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// Select multiplexer generic clock source and enable.
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GCLK->CLKCTRL.reg = GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK2 | sercom_gclk_id[id];
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// Wait while it updates synchronously.
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while (GCLK->STATUS.bit.SYNCBUSY) {
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}
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}
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