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91 lines
2.5 KiB
91 lines
2.5 KiB
/* |
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* Copyright (C) 2014 Loci Controls Inc. |
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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_cc2538 |
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* @{ |
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* |
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* @file |
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* @brief Implementation of the CPU initialization |
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* |
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* @author Ian Martin <ian@locicontrols.com> |
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* @} |
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*/ |
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#include <assert.h> |
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#include "cpu.h" |
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#include "periph/init.h" |
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#define BIT(n) ( 1UL << (n) ) |
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/* Select CLOCK_CTRL register bit masks: */ |
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#define OSC32K BIT(24) /**< 32-kHz clock oscillator selection */ |
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#define OSC_PD BIT(17) /**< Oscillator power-down */ |
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#define OSC BIT(16) /**< System clock oscillator selection */ |
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/* CLOCK_CTRL register field offsets: */ |
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#define IO_DIV_SHIFT 8 |
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#define SYS_DIV_SHIFT 0 |
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#define CLOCK_STA_MASK ( OSC32K | OSC ) |
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static void cpu_clock_init(void); |
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/** |
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* @brief Initialize the CPU, set IRQ priorities |
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*/ |
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void cpu_init(void) |
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{ |
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/* initialize the Cortex-M core */ |
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cortexm_init(); |
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/* Enable the CC2538's more compact alternate interrupt mapping */ |
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SYS_CTRL->I_MAP = 1; |
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/* initialize the clock system */ |
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cpu_clock_init(); |
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/* trigger static peripheral initialization */ |
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periph_init(); |
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} |
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/** |
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* @brief Configure the controllers clock system |
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*/ |
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static void cpu_clock_init(void) |
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{ |
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const uint32_t CLOCK_CTRL_VALUE = |
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OSC_PD /**< Power down the oscillator not selected by OSC bit (hardware-controlled when selected). */ |
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| (1 << IO_DIV_SHIFT) /**< 16 MHz IO_DIV */ |
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| (1 << SYS_DIV_SHIFT) /**< 16 MHz SYS_DIV */ |
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#if !SYS_CTRL_OSC32K_USE_XTAL |
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| OSC32K /**< Use internal RC oscillator. */ |
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#endif |
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; |
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#if SYS_CTRL_OSC32K_USE_XTAL |
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/* Set the XOSC32K_Q pads to analog for the external crystal: */ |
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gpio_software_control(GPIO_PD6); |
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gpio_dir_input(GPIO_PD6); |
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IOC_PXX_OVER[GPIO_PD6] = IOC_OVERRIDE_ANA; |
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gpio_software_control(GPIO_PD7); |
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gpio_dir_input(GPIO_PD7); |
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IOC_PXX_OVER[GPIO_PD7] = IOC_OVERRIDE_ANA; |
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#endif |
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/* Configure the clock settings: */ |
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SYS_CTRL->cc2538_sys_ctrl_clk_ctrl.CLOCK_CTRL = CLOCK_CTRL_VALUE; |
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/* Wait for the new clock settings to take effect: */ |
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while ((SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STA ^ CLOCK_CTRL_VALUE) & CLOCK_STA_MASK); |
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#if SYS_CTRL_OSC32K_USE_XTAL |
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/* Wait for the 32-kHz crystal oscillator to stabilize: */ |
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while ( SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K); |
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while (!SYS_CTRL->cc2538_sys_ctrl_clk_sta.CLOCK_STAbits.SYNC_32K); |
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#endif |
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}
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