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49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
/*
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* Copyright (C) 2021 Otto-von-Guericke Universität Magdeburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup cpu_rpx0xx
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* @{
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*
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* @file
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* @brief Implementation of the crystal oscillator (XOSC)
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*
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* @author Marian Buschsieweke <marian.buschsieweke@ovgu.de>
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* @author Fabian Hüßler <fabian.huessler@ovgu.de>
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*
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* @}
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*/
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#include <assert.h>
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#include "macros/units.h"
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#include "vendor/RP2040.h"
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#include "io_reg.h"
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static inline uint32_t _xosc_conf_sartup_delay(uint32_t f_crystal_mhz, uint32_t t_stable_ms)
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{
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return (((f_crystal_mhz / 1000) * t_stable_ms) + 128) / 256;
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}
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void xosc_start(uint32_t f_ref)
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{
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assert(f_ref == MHZ(12));
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uint32_t delay = _xosc_conf_sartup_delay(f_ref, 1);
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io_reg_write_dont_corrupt(&XOSC->STARTUP.reg, delay << XOSC_STARTUP_DELAY_Pos,
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XOSC_STARTUP_DELAY_Msk);
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io_reg_write_dont_corrupt(&XOSC->CTRL.reg, XOSC_CTRL_ENABLE_ENABLE << XOSC_CTRL_ENABLE_Pos,
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XOSC_CTRL_ENABLE_Msk);
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while (!XOSC->STATUS.bit.STABLE) { }
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}
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void xosc_stop(void)
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{
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io_reg_write_dont_corrupt(&XOSC->CTRL.reg, XOSC_CTRL_ENABLE_DISABLE << XOSC_CTRL_ENABLE_Pos,
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XOSC_CTRL_ENABLE_Msk);
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}
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