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113 lines
4.1 KiB
113 lines
4.1 KiB
//*****************************************************************************
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//
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//! @file system_apollo3.c
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//!
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//! @brief Ambiq Micro Apollo3 MCU specific functions.
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//
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//*****************************************************************************
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//*****************************************************************************
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//
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// Copyright (c) 2020, Ambiq Micro, Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its
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// contributors may be used to endorse or promote products derived from this
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// software without specific prior written permission.
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//
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// Third party software included in this distribution is subject to the
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// additional license terms as defined in the /docs/licenses directory.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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//*****************************************************************************
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#include <stdint.h>
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#include "system_apollo3.h"
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#include "apollo3.h"
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//*****************************************************************************
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//
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// Defines
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//
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//*****************************************************************************
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//
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// Clocks
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//
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#define __HSI (6000000UL)
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#define __XTAL (32768UL) // Crystal Oscillator frequency
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#define __SYS_OSC_CLK (48000000) // Main oscillator frequency
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#define __SYSTEM_CLOCK (1*__SYS_OSC_CLK)
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//
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// Initialize SystemCoreClock with the system core clock frequency value
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// achieved after system intitialization.
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// This means system core clock frequency after call to SystemInit()
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//
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uint32_t SystemCoreClock = __SYSTEM_CLOCK; // System Clock Frequency (Core Clock)
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//*****************************************************************************
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//
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//! @brief Set the global clock frequncy.
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//!
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//! This function sets the global clock frequency.
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//!
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//! @return None.
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//
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//*****************************************************************************
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void
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SystemCoreClockUpdate(void)
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{
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//
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// Calculate the system frequency based upon the current register settings.
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// This function can be used to retrieve the system core clock frequeny
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// after user changed register sittings.
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//
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SystemCoreClock = __SYS_OSC_CLK / (CLKGEN->CCTRL_b.CORESEL + 1);
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}
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//*****************************************************************************
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//
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//! @brief Initialize the system.
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//!
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//! This function sets up the microcontroller system.
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//!
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//! @return None.
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//
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//*****************************************************************************
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void
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SystemInit(void)
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{
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//
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// Initialize the system
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// Do not use global variables because this function is called before
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// reaching pre-main. RW section maybe overwritten afterwards.
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//
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SystemCoreClock = __SYSTEM_CLOCK;
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CLKGEN->CLKKEY = 0x47; // Enable write to CCTRL
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CLKGEN->CCTRL_b.CORESEL = 0; // Div by 1 for 48MHz
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CLKGEN->CLKKEY = 0; // Disable write to CCTRL
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}
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