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55 lines
1.9 KiB
C
55 lines
1.9 KiB
C
/**
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* @file xosc.c
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* @brief External crystal oscillator (XOSC) initialization and clock enable
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* @author Kevin Thomas
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* @date 2025
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*
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* MIT License
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*
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* Copyright (c) 2025 Kevin Thomas
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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 all
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* 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 THE
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* SOFTWARE.
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*/
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#include "xosc.h"
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#include "constants.h"
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void Init_XOSC(void) {
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// set delay 50,000 cycles
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XOSC->STARTUP = 0x00C4U;
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// set 1_15MHz, freq range, actual 14.5MHz
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XOSC->CTRL = 0x00FABAA0U;
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// wait until stable bit is set
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while ((XOSC->STATUS & (1U << XOSC_STATUS_STABLE_SHIFT)) == 0) {
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}
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}
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void Enable_XOSC_Peri_Clock(void) {
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uint32_t value;
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// read CLK_PERI_CTRL value
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value = CLOCKS->CLK_PERI_CTRL;
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// set ENABLE bit
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value |= (1U << CLOCKS_CLK_PERI_CTRL_ENABLE_SHIFT);
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// set AUXSRC: XOSC_CLKSRC
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value |= (CLOCKS_CLK_PERI_CTRL_AUXSRC_XOSC << CLOCKS_CLK_PERI_CTRL_AUXSRC_SHIFT);
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// store value into CLK_PERI_CTRL
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CLOCKS->CLK_PERI_CTRL = value;
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}
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