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/*
Copyright (c) 2015 Arduino LLC. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _DELAY_
#define _DELAY_
#ifdef __cplusplus
extern "C" {
#endif
#include <stdint.h>
#include "nrfx.h"
#include "variant.h"
/**
* \brief Returns the number of milliseconds since the Arduino board began running the current program.
*
* This number will overflow (go back to zero), after approximately 50 days.
*
* \return Number of milliseconds since the program started (uint32_t)
*/
extern uint32_t millis( void ) ;
/**
* \brief Returns the number of microseconds since the Arduino board began running the current program.
*
* This number will overflow (go back to zero), after approximately 70 minutes. On 16 MHz Arduino boards
* (e.g. Duemilanove and Nano), this function has a resolution of four microseconds (i.e. the value returned is
* always a multiple of four). On 8 MHz Arduino boards (e.g. the LilyPad), this function has a resolution
* of eight microseconds.
*
* \note There are 1,000 microseconds in a millisecond and 1,000,000 microseconds in a second.
*/
extern uint32_t micros( void ) ;
/**
* \brief Pauses the program for the amount of time (in miliseconds) specified as parameter.
* (There are 1000 milliseconds in a second.)
*
* \param dwMs the number of milliseconds to pause (uint32_t)
*/
extern void delay( uint32_t dwMs );
/**
* \brief Pauses the program for the amount of time (in microseconds) specified as parameter.
*
* \param dwUs the number of microseconds to pause (uint32_t)
*/
static __inline__ void delayMicroseconds( uint32_t ) __attribute__((always_inline, unused)) ;
static __inline__ void delayMicroseconds( uint32_t usec )
{
nrfx_coredep_delay_us(usec);
}
/**
* Enable DWT, required for delay_ns()
*/
void dwt_enable(void);
void dwt_disable(void);
/**
* Delay nano seconds, delay_ns() make use of DWT of debug core.
* dwt_enable() must be called previously.
* Note: nrf52 run at 64MHz
* - 1000 ns ~ 64 cycles
* - 500 ns ~ 32 cycles
* - 250 ns ~ 16 cycles
* - 125 ns ~ 8 cycles
*/
// Enable pragma when this bug is fixed https://bugs.launchpad.net/gcc-arm-embedded/+bug/1534360
// #pragma GCC push_options
// #pragma GCC optimize ("Ofast")
#define DELAY_CYCLE_CORRECTION 8 // ~125 ns overhead for delay_ns()
#define delay_ns(ns) \
do {\
register uint32_t _endtime = DWT->CYCCNT;\
_endtime += ((F_CPU/1000000)*ns)/1000 - DELAY_CYCLE_CORRECTION;\
while (DWT->CYCCNT < _endtime) {}\
} while(0)
// #pragma GCC pop_options
#ifdef __cplusplus
}
#endif
#endif /* _DELAY_ */
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