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e0365e0bf9
Fixes #5745 For AVR based boards, three defines must be defined AVR_CONTEXT_SWAP_INIT, AVR_CONTEXT_SWAP_INTERRUPT_VECT, and AVR_CONTEXT_SWAP_TRIGGER. These defines are used to trigger a software interrupt used for context switching. When AVR_CONTEXT_SWAP_INTERRUPT_VECT is handled, the scheduler is run and a context swap will happen if necessary, with the resulting thread starting following the reti instruction. This results in threads running at normal priority instead of at interrupt priority. Atmega devices do provide a pure software interrupt. The method used here for waspmote-pro and arduino-mega2560 is to use pin change interrupts, set the pin to act as an output, and toggle the value to simulate a software interrupt. The main limitation here is that a physical pin is now occupied and must be defined for each board supported by RIOT. On the plus side, it provides an easy method for detecting context swaps with an oscilloscope.
91 lines
2.0 KiB
C
91 lines
2.0 KiB
C
/*
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* Copyright (C) 2014 Freie Universität Berlin, Hinnerk van Bruinehsen
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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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* @defgroup boards_arduino-mega2560 Arduino Mega 2560
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* @ingroup boards
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* @brief Board specific files for the Arduino Mega 2560 board.
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* @{
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*
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* @file
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* @brief Board specific definitions for the Arduino Mega 2560 board.
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*
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* @author Hinnerk van Bruinehsen <h.v.bruinehsen@fu-berlin.de>
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*/
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#ifndef BOARD_H_
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#define BOARD_H_
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#include "cpu.h"
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#include "arduino_pinmap.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Use the UART 0 for STDIO on this board
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*/
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#define UART_STDIO_DEV UART_DEV(0)
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/**
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* @brief As the CPU is too slow to handle 115200 baud, we set the default
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* baudrate to 9600 for this board
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*/
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#define UART_STDIO_BAUDRATE (9600U)
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/**
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* @brief LED pin definitions and handlers
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* @{
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*/
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#define LED0_PIN GPIO_PIN(1, 7)
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#define LED0_MASK (1 << DDB7)
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#define LED0_ON (PORTB |= LED0_MASK)
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#define LED0_OFF (PORTB &= ~LED0_MASK)
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#define LED0_TOGGLE (PORTB ^= LED0_MASK)
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/** @} */
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/**
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* Context swap defines
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* Setup to use PJ6 which is pin change interrupt 15 (PCINT15)
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* This emulates a software triggered interrupt
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**/
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#define AVR_CONTEXT_SWAP_INIT do { \
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DDRJ |= (1 << PJ6); \
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PCICR |= (1 << PCIE1); \
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PCMSK1 |= (1 << PCINT15); \
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} while (0)
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#define AVR_CONTEXT_SWAP_INTERRUPT_VECT PCINT1_vect
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#define AVR_CONTEXT_SWAP_TRIGGER PORTJ ^= (1 << PJ6)
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/**
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* @brief xtimer configuration values
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* @{
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*/
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#define XTIMER_WIDTH (16)
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#define XTIMER_SHIFT (2)
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#define XTIMER_BACKOFF (40)
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/** @} */
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/**
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* @brief Initialize board specific hardware, including clock, LEDs and std-IO
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*/
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void board_init(void);
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#ifdef __cplusplus
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}
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#endif
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#endif /* BOARD_H_ */
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/** @} */
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