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_CTxxBx_Type *)LPC_CT32B1_BASE)
21 #define US_TICKER_TIMER_IRQn TIMER_32_1_IRQn
23 int us_ticker_inited = 0;
25 void us_ticker_init(void) {
26 if (us_ticker_inited) return;
29 LPC_SYSCON->SYSAHBCLKCTRL |= (1<<10); // Clock TIMER_1
30 uint32_t PCLK = SystemCoreClock;
32 US_TICKER_TIMER->TCR = 0x2; // reset
34 uint32_t prescale = PCLK / 1000000; // default to 1MHz (1 us ticks)
35 US_TICKER_TIMER->PR = prescale - 1;
36 US_TICKER_TIMER->TCR = 1; // enable = 1, reset = 0
38 NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
39 NVIC_EnableIRQ(US_TICKER_TIMER_IRQn);
42 uint32_t us_ticker_read() {
43 if (!us_ticker_inited)
46 return US_TICKER_TIMER->TC;
49 void us_ticker_set_interrupt(timestamp_t timestamp) {
51 US_TICKER_TIMER->MR0 = (uint32_t)timestamp;
52 // enable match interrupt
53 US_TICKER_TIMER->MCR |= 1;
56 void us_ticker_disable_interrupt(void) {
57 US_TICKER_TIMER->MCR &= ~1;
60 void us_ticker_clear_interrupt(void) {
61 US_TICKER_TIMER->IR = 1;