mirror of
https://github.com/RIOT-OS/RIOT.git
synced 2024-12-29 04:50:03 +01:00
109 lines
2.2 KiB
C
109 lines
2.2 KiB
C
/*
|
|
* Copyright (C) 2017,2020 Freie Universität Berlin
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU Lesser
|
|
* General Public License v2.1. See the file LICENSE in the top level
|
|
* directory for more details.
|
|
*/
|
|
|
|
/**
|
|
* @ingroup cpu_sam3
|
|
* @ingroup drivers_periph_rtt
|
|
*
|
|
* @note The hardware RTT unit does neither support overflow interrupts
|
|
* nor setting the counter value. For this, this RTT driver does
|
|
* not implement those functions.
|
|
* @{
|
|
*
|
|
* @file
|
|
* @brief Low-level RTT driver implementation
|
|
*
|
|
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
|
|
*
|
|
* @}
|
|
*/
|
|
|
|
#include "cpu.h"
|
|
#include "periph/rtt.h"
|
|
|
|
#define ENABLE_DEBUG 0
|
|
#include "debug.h"
|
|
|
|
static struct {
|
|
rtt_cb_t cb;
|
|
void *arg;
|
|
} isr_ctx;
|
|
|
|
void rtt_init(void)
|
|
{
|
|
/* enable RTT module */
|
|
rtt_poweron();
|
|
|
|
/* configure and apply the pre-scaler */
|
|
RTT->RTT_MR = RTT_MR_RTPRES(CHIP_FREQ_XTAL_32K / RTT_FREQUENCY);
|
|
RTT->RTT_MR |= RTT_MR_RTTRST;
|
|
|
|
/* resetting the timer takes two slow clock cycles, so we wait for this to
|
|
* complete */
|
|
while (RTT->RTT_VR != 0) {}
|
|
|
|
/* configure NVIC line */
|
|
NVIC_EnableIRQ(RTT_IRQn);
|
|
}
|
|
|
|
uint32_t rtt_get_counter(void)
|
|
{
|
|
return RTT->RTT_VR;
|
|
}
|
|
|
|
void rtt_set_alarm(uint32_t alarm, rtt_cb_t cb, void *arg)
|
|
{
|
|
/* cancel any existing alarm */
|
|
RTT->RTT_MR &= ~(RTT_MR_ALMIEN);
|
|
|
|
/* set new alarm */
|
|
isr_ctx.cb = cb;
|
|
isr_ctx.arg = arg;
|
|
/* the alarm value is RTT_AR + 1, so we need to subtract 1 from the target
|
|
* value here */
|
|
RTT->RTT_AR = (alarm - 1);
|
|
|
|
/* (re-)enable the alarm */
|
|
RTT->RTT_MR |= RTT_MR_ALMIEN;
|
|
}
|
|
|
|
uint32_t rtt_get_alarm(void)
|
|
{
|
|
if (RTT->RTT_MR & RTT_MR_ALMIEN) {
|
|
/* the alarm value is RTT_AR + 1, see rtt_set_alarm() */
|
|
return RTT->RTT_AR + 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void rtt_clear_alarm(void)
|
|
{
|
|
RTT->RTT_MR &= ~(RTT_MR_ALMIEN);
|
|
}
|
|
|
|
void rtt_poweron(void)
|
|
{
|
|
PMC->PMC_PCER0 |= (1 << ID_RTT);
|
|
}
|
|
|
|
void rtt_poweroff(void)
|
|
{
|
|
PMC->PMC_PCER0 &= ~(1 << ID_RTT);
|
|
}
|
|
|
|
void isr_rtt(void)
|
|
{
|
|
uint32_t state = RTT->RTT_SR; /* this clears all pending flags */
|
|
if (state & RTT_SR_ALMS) {
|
|
RTT->RTT_MR &= ~(RTT_MR_ALMIEN);
|
|
isr_ctx.cb(isr_ctx.arg);
|
|
}
|
|
|
|
cortexm_isr_end();
|
|
}
|