/* * This file is part of the MicroPython project, http://micropython.org/ * * This file provides functions for configuring the clocks. * * The MIT License (MIT) * * Copyright (c) 2022 Robert Hammelrath * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include #include "py/runtime.h" #include "py/mphal.h" #include "samd_soc.h" static uint32_t cpu_freq = CPU_FREQ; static uint32_t peripheral_freq = DFLL48M_FREQ; static uint32_t dfll48m_calibration; int sercom_gclk_id[] = { GCLK_CLKCTRL_ID_SERCOM0_CORE, GCLK_CLKCTRL_ID_SERCOM1_CORE, GCLK_CLKCTRL_ID_SERCOM2_CORE, GCLK_CLKCTRL_ID_SERCOM3_CORE, GCLK_CLKCTRL_ID_SERCOM4_CORE, GCLK_CLKCTRL_ID_SERCOM5_CORE }; uint32_t get_cpu_freq(void) { return cpu_freq; } uint32_t get_peripheral_freq(void) { return peripheral_freq; } void set_cpu_freq(uint32_t cpu_freq_arg) { // Set 1 wait state to be safe NVMCTRL->CTRLB.reg = NVMCTRL_CTRLB_MANW | NVMCTRL_CTRLB_RWS(1); int div = MAX(DFLL48M_FREQ / cpu_freq_arg, 1); peripheral_freq = DFLL48M_FREQ / div; // Enable GCLK output: 48MHz from DFLL48M on both CCLK0 and GCLK2 GCLK->GENDIV.reg = GCLK_GENDIV_ID(0) | GCLK_GENDIV_DIV(div); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(0); while (GCLK->STATUS.bit.SYNCBUSY) { } GCLK->GENDIV.reg = GCLK_GENDIV_ID(2) | GCLK_GENDIV_DIV(div); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(2); while (GCLK->STATUS.bit.SYNCBUSY) { } // The comparison is >=, such that for 48MHz still the FDPLL96 is used for the CPU clock. if (cpu_freq_arg >= 48000000) { cpu_freq = cpu_freq_arg; // Connect GCLK1 to the FDPLL96 input. GCLK->CLKCTRL.reg = GCLK_CLKCTRL_GEN_GCLK1 | GCLK_CLKCTRL_ID_FDPLL | GCLK_CLKCTRL_CLKEN; while (GCLK->STATUS.bit.SYNCBUSY) { } // configure the FDPLL96 // CtrlB: Set the ref source to GCLK, set the Wakeup-Fast Flag. SYSCTRL->DPLLCTRLB.reg = SYSCTRL_DPLLCTRLB_REFCLK_GCLK | SYSCTRL_DPLLCTRLB_WUF; // Set the FDPLL ratio and enable the DPLL. int ldr = cpu_freq / FDPLL_REF_FREQ; int frac = ((cpu_freq - ldr * FDPLL_REF_FREQ) / (FDPLL_REF_FREQ / 16)) & 0x0f; SYSCTRL->DPLLRATIO.reg = SYSCTRL_DPLLRATIO_LDR((frac << 16 | ldr) - 1); SYSCTRL->DPLLCTRLA.reg = SYSCTRL_DPLLCTRLA_ENABLE; // Wait for the DPLL lock. while (!SYSCTRL->DPLLSTATUS.bit.LOCK) { } // Finally switch GCLK0 to FDPLL96M. GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DPLL96M | GCLK_GENCTRL_ID(0); while (GCLK->STATUS.bit.SYNCBUSY) { } } else { cpu_freq = peripheral_freq; // Disable the FDPLL96M in case it was enabled. SYSCTRL->DPLLCTRLA.reg = 0; } if (cpu_freq >= 8000000) { // Enable GCLK output: 48MHz on GCLK5 for USB GCLK->GENDIV.reg = GCLK_GENDIV_ID(5) | GCLK_GENDIV_DIV(1); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(5); while (GCLK->STATUS.bit.SYNCBUSY) { } } else { // Disable GCLK output on GCLK5 for USB, since USB is not reliable below 8 Mhz. GCLK->GENCTRL.reg = GCLK_GENCTRL_ID(5); while (GCLK->STATUS.bit.SYNCBUSY) { } } // Set 0 wait states for slower CPU clock NVMCTRL->CTRLB.reg = NVMCTRL_CTRLB_MANW | NVMCTRL_CTRLB_RWS(cpu_freq > 24000000 ? 1 : 0); SysTick_Config(cpu_freq / 1000); } void check_usb_recovery_mode(void) { #if !MICROPY_HW_XOSC32K // Check USB status for up to 1 second. If not connected, // switch DFLL48M back to open loop for (int i = 0; i < 100; i++) { if (USB->DEVICE.DeviceEndpoint[0].EPCFG.reg != 0) { return; } mp_hal_delay_ms(10); } // Set/keep the open loop mode of the device. SYSCTRL->DFLLVAL.reg = dfll48m_calibration; SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_CCDIS | SYSCTRL_DFLLCTRL_ENABLE; #endif // MICROPY_HW_XOSC32K } // Purpose of the #defines for the clock configuration. // // The CPU is either driven by the FDPLL96 oscillator for f >= 48MHz, // or by the DFLL48M for lower frequencies. The FDPLL96 takes 32768 Hz // as reference frequency, supplied through GCLK1. // // DFLL48M is used for the peripheral clock, e.g. for PWM, UART, SPI, I2C. // DFLL48M is either free running, or controlled by the 32kHz crystal, or // Synchronized with the USB clock. // Both CPU and peripheral devices are clocked by the DFLL48M clock. // DFLL48M is either free running, or controlled by the 32kHz crystal, or // Synchronized with the USB clock. // // #define MICROPY_HW_XOSC32K (0 | 1) // // If MICROPY_HW_XOSC32K = 1, the 32kHz crystal is used as input for GCLK 1, which // serves as reference clock source for the DFLL48M oscillator, // The crystal is used, unless MICROPY_HW_MCU_OSC32KULP is set. // In that case GCLK1 (and the CPU clock) is driven by the 32K Low power oscillator. // The reason for offering this option is a design flaw of the Adafruit // Feather boards, where the RGB LED and Debug signals interfere with the // crystal, causing the CPU to fail if it is driven by the crystal. // // If MICROPY_HW_XOSC32K = 0, the 32kHz signal for GCLK1 (and the CPU) is // created by dividing the 48MHz clock of DFLL48M, but not used otherwise. // // If MICROPY_HW_DFLL_USB_SYNC = 0, the DFLL48M oscillator is free running using // the pre-configured trim values. In that mode, the peripheral clock is // not exactly 48Mhz and has a substitutional temperature drift. // // If MICROPY_HW_DFLL_USB_SYNC = 1, the DFLL48 is synchronized with the 1 kHz USB sync // signal. If after boot there is no USB sync within 1000 ms, the configuration falls // back to a free running 48Mhz oscillator. // // In all modes, the 48MHz signal has a substantial jitter, largest when // MICROPY_HW_DFLL_USB_SYNC is active. That is caused by the respective // reference frequencies of 32kHz or 1 kHz being low. That affects most // PWM. Std Dev at 1kHz 0.156Hz (w. Crystal) up to 0.4 Hz (with USB sync). // // If none of the mentioned defines is set, the device uses the internal oscillators. void init_clocks(uint32_t cpu_freq) { dfll48m_calibration = 0; // please the compiler // SAMD21 Clock settings // // GCLK0: 48MHz, source: DFLL48M or FDPLL96M, usage: CPU // GCLK1: 32kHz, source: XOSC32K or OSCULP32K, usage: FDPLL96M reference // GCLK2: 1-48MHz, source: DFLL48M, usage: Peripherals // GCLK3: 2Mhz, source: DFLL48M, usage: us-counter (TC4/TC5) // GCLK4: 32kHz, source: XOSC32K, if crystal present, usage: DFLL48M reference // GCLK5: 48MHz, source: DFLL48M, usage: USB // GCLK8: 1kHz, source: XOSC32K or OSCULP32K, usage: WDT and RTC // DFLL48M: Reference sources: // - in closed loop mode: either XOSC32K or OSCULP32K or USB clock // from GCLK4. // - in open loop mode: None // FDPLL96M: Reference source GCLK1 // Used for the CPU clock for freq >= 48Mhz NVMCTRL->CTRLB.bit.MANW = 1; // errata "Spurious Writes" NVMCTRL->CTRLB.bit.RWS = 1; // 1 read wait state for 48MHz #if MICROPY_HW_XOSC32K // Set up OSC32K according data sheet 17.6.3 SYSCTRL->XOSC32K.reg = SYSCTRL_XOSC32K_STARTUP(0x3) | SYSCTRL_XOSC32K_EN32K | SYSCTRL_XOSC32K_XTALEN; SYSCTRL->XOSC32K.bit.ENABLE = 1; while (SYSCTRL->PCLKSR.bit.XOSC32KRDY == 0) { } // Set up the DFLL48 according to the data sheet 17.6.7.1.2 // Step 1: Set up the reference clock #if MICROPY_HW_MCU_OSC32KULP // Connect the GCLK1 to the XOSC32KULP GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(1); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(1); #else // Connect the GCLK1 to OSC32K GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(1); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(1); #endif while (GCLK->STATUS.bit.SYNCBUSY) { } // Connect the GCLK4 to OSC32K GCLK->GENDIV.reg = GCLK_GENDIV_ID(4) | GCLK_GENDIV_DIV(1); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(4); // Connect GCLK4 to the DFLL input. GCLK->CLKCTRL.reg = GCLK_CLKCTRL_GEN_GCLK4 | GCLK_CLKCTRL_ID_DFLL48 | GCLK_CLKCTRL_CLKEN; while (GCLK->STATUS.bit.SYNCBUSY) { } // Enable access to the DFLLCTRL register according to Errata 1.2.1 SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_ENABLE; while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) { } // Step 2: Set the coarse and fine values. // Get the coarse value from the calibration data. In case it is not set, // set a midrange value. uint32_t coarse = (*((uint32_t *)FUSES_DFLL48M_COARSE_CAL_ADDR) & FUSES_DFLL48M_COARSE_CAL_Msk) >> FUSES_DFLL48M_COARSE_CAL_Pos; if (coarse == 0x3f) { coarse = 0x1f; } SYSCTRL->DFLLVAL.reg = SYSCTRL_DFLLVAL_COARSE(coarse) | SYSCTRL_DFLLVAL_FINE(512); while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) { } // Step 3: Set the multiplication values. The offset of 16384 to the freq is for rounding. SYSCTRL->DFLLMUL.reg = SYSCTRL_DFLLMUL_MUL((CPU_FREQ + 16384) / 32768) | SYSCTRL_DFLLMUL_FSTEP(1) | SYSCTRL_DFLLMUL_CSTEP(1); while (SYSCTRL->PCLKSR.bit.DFLLRDY == 0) { } // Step 4: Start the DFLL and wait for the PLL lock. We just wait for the fine lock, since // coarse adjusting is bypassed. SYSCTRL->DFLLCTRL.reg |= SYSCTRL_DFLLCTRL_MODE | SYSCTRL_DFLLCTRL_WAITLOCK | SYSCTRL_DFLLCTRL_STABLE | SYSCTRL_DFLLCTRL_BPLCKC | SYSCTRL_DFLLCTRL_ENABLE; while (SYSCTRL->PCLKSR.bit.DFLLLCKF == 0) { } // Set GCLK8 to 1 kHz. GCLK->GENDIV.reg = GCLK_GENDIV_ID(8) | GCLK_GENDIV_DIV(32); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_XOSC32K | GCLK_GENCTRL_ID(8); while (GCLK->STATUS.bit.SYNCBUSY) { } #else // MICROPY_HW_XOSC32K // Enable DFLL48M SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_ENABLE; while (!SYSCTRL->PCLKSR.bit.DFLLRDY) { } uint32_t coarse = (*((uint32_t *)FUSES_DFLL48M_COARSE_CAL_ADDR) & FUSES_DFLL48M_COARSE_CAL_Msk) >> FUSES_DFLL48M_COARSE_CAL_Pos; if (coarse == 0x3f) { coarse = 0x1f; } SYSCTRL->DFLLVAL.reg = SYSCTRL_DFLLVAL_COARSE(coarse) | SYSCTRL_DFLLVAL_FINE(511); #if MICROPY_HW_DFLL_USB_SYNC // Configure the DFLL48M for USB clock recovery. // Will have to switch back if no USB SYSCTRL->DFLLSYNC.bit.READREQ = 1; dfll48m_calibration = SYSCTRL->DFLLVAL.reg; // Set the Multiplication factor. SYSCTRL->DFLLMUL.reg = SYSCTRL_DFLLMUL_CSTEP(1) | SYSCTRL_DFLLMUL_FSTEP(1) | SYSCTRL_DFLLMUL_MUL(48000); // Set the mode to closed loop USB Recovery mode SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_USBCRM | SYSCTRL_DFLLCTRL_CCDIS | SYSCTRL_DFLLCTRL_MODE | SYSCTRL_DFLLCTRL_ENABLE; #else // Set/keep the open loop mode of the device. SYSCTRL->DFLLCTRL.reg = SYSCTRL_DFLLCTRL_CCDIS | SYSCTRL_DFLLCTRL_ENABLE; #endif while (!SYSCTRL->PCLKSR.bit.DFLLRDY) { } // Connect the GCLK1 to the XOSC32KULP GCLK->GENDIV.reg = GCLK_GENDIV_ID(1) | GCLK_GENDIV_DIV(1); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(1); while (GCLK->STATUS.bit.SYNCBUSY) { } // Set GCLK8 to 1 kHz. GCLK->GENDIV.reg = GCLK_GENDIV_ID(8) | GCLK_GENDIV_DIV(32); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSCULP32K | GCLK_GENCTRL_ID(8); while (GCLK->STATUS.bit.SYNCBUSY) { } #endif // MICROPY_HW_XOSC32K set_cpu_freq(cpu_freq); // Enable GCLK output: 2MHz on GCLK3 for TC4 GCLK->GENDIV.reg = GCLK_GENDIV_ID(3) | GCLK_GENDIV_DIV(24); GCLK->GENCTRL.reg = GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_DFLL48M | GCLK_GENCTRL_ID(3); while (GCLK->STATUS.bit.SYNCBUSY) { } } void enable_sercom_clock(int id) { // Enable synchronous clock. The bits are nicely arranged PM->APBCMASK.reg |= 0x04 << id; // Select multiplexer generic clock source and enable. GCLK->CLKCTRL.reg = GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK2 | sercom_gclk_id[id]; // Wait while it updates synchronously. while (GCLK->STATUS.bit.SYNCBUSY) { } }