Mouse code for the MacroRat
Diff: mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c
- Revision:
- 18:6a4db94011d3
diff -r f713758f6238 -r 6a4db94011d3 mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/us_ticker.c Sun May 14 23:18:57 2017 +0000 @@ -0,0 +1,84 @@ +/* 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; + +}