Mouse code for the MacroRat
mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c
- Committer:
- sahilmgandhi
- Date:
- 2017-06-03
- Revision:
- 46:b156ef445742
- Parent:
- 18:6a4db94011d3
File content as of revision 46:b156ef445742:
/* mbed Microcontroller Library * Copyright (c) 2006-2015 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include <stddef.h> #include "us_ticker_api.h" #include "PeripheralNames.h" #include "clk_freqs.h" static int us_ticker_inited = 0; void us_ticker_init(void) { if (us_ticker_inited) return; us_ticker_inited = 1; SIM->SCGC6 |= SIM_SCGC6_PIT_MASK; // Clock PIT PIT->MCR = 0; // Enable PIT //Timer on PIT0+1, ticker on PIT 2+3 //Init timer PIT->CHANNEL[1].LDVAL = 0xFFFFFFFF; PIT->CHANNEL[1].TCTRL = PIT_TCTRL_CHN_MASK | PIT_TCTRL_TEN_MASK; // Start timer 1, chained to timer 0 // Use channel 0 as a prescaler for channel 1 uint32_t ldval = (bus_frequency() + 500000) / 1000000 - 1; PIT->CHANNEL[0].LDVAL = ldval; PIT->CHANNEL[0].TCTRL = PIT_TCTRL_TEN_MASK; // Start timer //Init ticker PIT->CHANNEL[2].LDVAL = ldval; PIT->CHANNEL[2].TCTRL = PIT_TCTRL_TEN_MASK; // Start timer 2 as prescaler NVIC_SetVector(PIT3_IRQn, (uint32_t)us_ticker_irq_handler); NVIC_EnableIRQ(PIT3_IRQn); } /****************************************************************************** * Timer for us timing. ******************************************************************************/ uint32_t us_ticker_read() { if (!us_ticker_inited) us_ticker_init(); return ~(PIT->CHANNEL[1].CVAL); } /****************************************************************************** * Ticker Event ******************************************************************************/ void us_ticker_disable_interrupt(void) { PIT->CHANNEL[3].TCTRL &= ~PIT_TCTRL_TIE_MASK; } void us_ticker_clear_interrupt(void) { PIT->CHANNEL[3].TFLG = 1; } void us_ticker_set_interrupt(timestamp_t timestamp) { int delta = (int)((uint32_t)timestamp - us_ticker_read()); if (delta <= 0) { // This event was in the past: us_ticker_irq_handler(); return; } PIT->CHANNEL[3].TCTRL = 0; PIT->CHANNEL[3].LDVAL = delta; PIT->CHANNEL[3].TCTRL = PIT_TCTRL_TIE_MASK | PIT_TCTRL_TEN_MASK | PIT_TCTRL_CHN_MASK; }