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git.gir.st - tmk_keyboard.git/blob - tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/us_ticker.c
1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include "us_ticker_api.h"
18 #include "PeripheralNames.h"
20 #define US_TICKER_TIMER ((LPC_TIM_TypeDef *)LPC_TIM3_BASE)
21 #define US_TICKER_TIMER_IRQn TIMER3_IRQn
23 int us_ticker_inited
= 0;
25 void us_ticker_init(void) {
26 if (us_ticker_inited
) return;
29 LPC_SC
->PCONP
|= 1 << 23; // Clock TIMER_3
31 US_TICKER_TIMER
->CTCR
= 0x0; // timer mode
32 uint32_t PCLK
= SystemCoreClock
/ 4;
34 US_TICKER_TIMER
->TCR
= 0x2; // reset
36 uint32_t prescale
= PCLK
/ 1000000; // default to 1MHz (1 us ticks)
37 US_TICKER_TIMER
->PR
= prescale
- 1;
38 US_TICKER_TIMER
->TCR
= 1; // enable = 1, reset = 0
40 NVIC_SetVector(US_TICKER_TIMER_IRQn
, (uint32_t)us_ticker_irq_handler
);
41 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn
);
44 uint32_t us_ticker_read() {
45 if (!us_ticker_inited
)
48 return US_TICKER_TIMER
->TC
;
51 void us_ticker_set_interrupt(timestamp_t timestamp
) {
53 US_TICKER_TIMER
->MR0
= (uint32_t)timestamp
;
54 // enable match interrupt
55 US_TICKER_TIMER
->MCR
|= 1;
58 void us_ticker_disable_interrupt(void) {
59 US_TICKER_TIMER
->MCR
&= ~1;
62 void us_ticker_clear_interrupt(void) {
63 US_TICKER_TIMER
->IR
= 1;