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128 lines
3.6 KiB
128 lines
3.6 KiB
/* |
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* Copyright (C) 2014 Freie Universität Berlin |
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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 |
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* @{ |
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* |
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* @file |
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* @brief low-power mode implementation for MSP430 MCUs |
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* |
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* @author Kévin Roussel <Kevin.Roussel@inria.fr> |
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* @author Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de> |
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* @author Thomas Eichinger <thomas.eichinger@fu-berlin.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 <stdio.h> |
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#if (__GNUC__ >= 4) && (__GNUC_MINOR__ > 5) |
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#include <intrinsics.h> // MSP430-gcc compiler instrinsics |
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#endif |
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#include "board.h" |
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#include <msp430.h> |
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#include "lpm.h" |
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/* Initialise the MSP430 power-saving mechanisms. */ |
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void lpm_init(void) |
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{ |
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/* nothing to initialize on MSP430s: everything is done by fiddling |
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with 4 bits of the status register (SR). */ |
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/* just ensure MCU is fully up and running at start */ |
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lpm_awake(); |
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} |
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/* Change the current power-saving mode. */ |
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enum lpm_mode lpm_set(enum lpm_mode target) |
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{ |
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enum lpm_mode last_mode = lpm_get(); |
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/* ensure that interrupts are enabled before going to sleep, |
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or we're bound to hang our MCU! */ |
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assert((target == LPM_ON) || (__read_status_register() & GIE)); |
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switch (target) { |
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case LPM_ON: |
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/* fully running MCU */ |
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__bic_status_register(CPUOFF | OSCOFF | SCG0 | SCG1); |
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break; |
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case LPM_IDLE: |
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/* lightest mode => LPM0 mode of MSP430 */ |
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__bic_status_register(OSCOFF | SCG0 | SCG1); |
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/* only stops CPU block */ |
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__bis_status_register(CPUOFF); |
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break; |
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case LPM_SLEEP: |
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/* mid-level mode => LPM1 mode of MSP430 */ |
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__bic_status_register(OSCOFF | SCG1); |
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/* stops CPU and master clock blocks */ |
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__bis_status_register(CPUOFF | SCG0); |
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break; |
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case LPM_POWERDOWN: |
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/* deep-level mode => LPM3 mode of MSP430 */ |
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__bic_status_register(OSCOFF); |
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/* stops all blocks except auxiliary clock (timers) */ |
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__bis_status_register(CPUOFF | SCG0 | SCG1); |
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break; |
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case LPM_OFF: |
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/* MCU totally down (LPM4), only RESET or NMI can resume execution */ |
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__bis_status_register(CPUOFF | OSCOFF | SCG0 | SCG1); |
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/* all blocks off */ |
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break; |
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default: |
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assert(0); /* abort if NDEBUG is not defined */ |
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break; |
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} |
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return last_mode; |
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} |
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#define LPM_MASK_SR (CPUOFF | OSCOFF | SCG0 | SCG1) |
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/* Return the current LPM mode of the MSP430 MCU. */ |
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enum lpm_mode lpm_get(void) |
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{ |
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enum lpm_mode current_mode = LPM_UNKNOWN; |
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unsigned int current_sr = __read_status_register(); |
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switch (current_sr & LPM_MASK_SR) { |
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case CPUOFF + OSCOFF + SCG0 + SCG1: /* MSP430's LPM4 */ |
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current_mode = LPM_OFF; |
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break; |
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case CPUOFF + SCG0 + SCG1: /* MSP430's LPM3 */ |
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case CPUOFF + SCG1: /* MSP430's LPM2 */ |
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current_mode = LPM_POWERDOWN; |
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break; |
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case CPUOFF + SCG0: /* MSP430's LPM1 */ |
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current_mode = LPM_SLEEP; |
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break; |
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case CPUOFF: /* MSP430's LPM1 */ |
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current_mode = LPM_IDLE; |
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break; |
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case 0: /* MSP430 active */ |
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current_mode = LPM_ON; |
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break; |
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} |
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return current_mode; |
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} |
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/* resume the MSP430 MCU */ |
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inline void lpm_awake(void) |
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{ |
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/* disable all power savings mechanisms */ |
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__bic_status_register(CPUOFF | OSCOFF | SCG0 | SCG1); |
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} |
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/* the following two functions have no actual role to play MSP430s */ |
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inline void lpm_begin_awake(void) { } |
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inline void lpm_end_awake(void) { }
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