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86 lines
2.8 KiB
C
86 lines
2.8 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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* The MIT License (MIT)
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*
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* Copyright (c) 2025 Ibrahim Abdelkader <iabdalkader@openmv.io>
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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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// CPU frequency
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#ifndef CPU_FREQ_HZ
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#define CPU_FREQ_HZ 25000000u
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#endif
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// SysTick registers
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#define SYSTICK_BASE 0xE000E010
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#define SYSTICK_CSR (*(volatile uint32_t *)(SYSTICK_BASE + 0x00))
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#define SYSTICK_RVR (*(volatile uint32_t *)(SYSTICK_BASE + 0x04))
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#define SYSTICK_CVR (*(volatile uint32_t *)(SYSTICK_BASE + 0x08))
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// SysTick config bits
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#define SYSTICK_CSR_ENABLE (1 << 0)
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#define SYSTICK_CSR_TICKINT (1 << 1)
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#define SYSTICK_CSR_CLKSOURCE (1 << 2)
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static volatile uint32_t _ticks_ms = 0;
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#if defined(__ARM_ARCH_ISA_ARM)
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static volatile uint32_t _ticks_us = 0;
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#endif
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void ticks_init(void) {
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#if !defined(__ARM_ARCH_ISA_ARM)
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// Configure SysTick: reload at 1ms intervals (Cortex-M)
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SYSTICK_CVR = 0;
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SYSTICK_RVR = (CPU_FREQ_HZ / 1000) - 1;
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SYSTICK_CSR = SYSTICK_CSR_ENABLE | SYSTICK_CSR_TICKINT | SYSTICK_CSR_CLKSOURCE;
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#endif
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}
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uintptr_t ticks_ms(void) {
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#if defined(__ARM_ARCH_ISA_ARM)
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return _ticks_us++ / 1000;
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#else
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return _ticks_ms;
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#endif
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}
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uintptr_t ticks_us(void) {
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#if defined(__ARM_ARCH_ISA_ARM)
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return _ticks_us++;
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#else
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// Get current values atomically
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uint32_t ms = _ticks_ms;
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uint32_t cvr = SYSTICK_CVR;
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// Calculate microseconds from the down-counter
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uint32_t elapsed_cycles = SYSTICK_RVR - cvr;
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uint32_t us_fraction = (elapsed_cycles * 1000) / (CPU_FREQ_HZ / 1000);
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return (ms * 1000) + us_fraction;
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#endif
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}
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void SysTick_Handler(void) {
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_ticks_ms++;
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}
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