207 lines
6.2 KiB
C
207 lines
6.2 KiB
C
//*****************************************************************************
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//
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//! @file clkout.c
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//!
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//! @brief Enables a clock source to clkout and then tracks it on an LED array.
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//!
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//! This example enables the LFRC to a clkout pin then uses GPIO polling to
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//! track its rising edge and toggle an LED at 1 hertz.
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//
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//*****************************************************************************
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//*****************************************************************************
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//
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// Copyright (c) 2020, Ambiq Micro
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its
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// contributors may be used to endorse or promote products derived from this
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// software without specific prior written permission.
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//
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// Third party software included in this distribution is subject to the
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// additional license terms as defined in the /docs/licenses directory.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// This is part of revision 2.4.2 of the AmbiqSuite Development Package.
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//
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//*****************************************************************************
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#include "am_mcu_apollo.h"
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#include "am_bsp.h"
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#include "am_util.h"
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//*****************************************************************************
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//
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// Macro definitions
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//
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//*****************************************************************************
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#define RISING_EDGE_COUNT 500 // Turn 500 Hz (LFRC/2) clkout into 1 Hz blinky
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//*****************************************************************************
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//
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// Main function.
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//
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//*****************************************************************************
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int
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main(void)
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{
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int32_t iRisingCount, iLEDcount;
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bool bNewClkout, bOldClkout;
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//
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// Set the clock frequency.
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//
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am_hal_clkgen_sysclk_select(AM_HAL_CLKGEN_SYSCLK_MAX);
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//
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// Set the default cache configuration
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//
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am_hal_cachectrl_enable(&am_hal_cachectrl_defaults);
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//
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// Configure the board for low power operation.
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//
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am_bsp_low_power_init();
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//
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// Initialize the printf interface for ITM/SWO output.
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//
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am_util_stdio_printf_init((am_util_stdio_print_char_t) am_bsp_itm_string_print);
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//
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// Initialize the SWO GPIO pin
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//
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am_bsp_pin_enable(ITM_SWO);
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//
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// Enable the ITM.
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//
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am_hal_itm_enable();
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//
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// Enable debug printf messages using ITM on SWO pin
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//
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am_bsp_debug_printf_enable();
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//
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// Clear the terminal and print the banner.
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//
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am_util_stdio_terminal_clear();
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am_util_stdio_printf("CLKOUT to LED Example\n");
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am_util_stdio_printf("\tWalks the board LEDs about once a second based on the CLKOUT "
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"signal.\n");
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//
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// We are done printing. Disable debug printf messages on ITM.
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//
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am_bsp_debug_printf_disable();
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//
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// Clear the LED.
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//
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am_devices_led_array_init(am_bsp_psLEDs, AM_BSP_NUM_LEDS);
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//
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// Enable the LFRC.
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//
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am_hal_clkgen_osc_start(AM_HAL_CLKGEN_OSC_LFRC);
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//
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// Enable the clockout to the desired pin.
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// And make it readable on the pin with AM_HAL_GPIO_INPEN
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//
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am_hal_gpio_pin_config(AM_BSP_GPIO_CLKOUT_PIN,
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(AM_BSP_GPIO_CFG_CLKOUT_PIN | AM_HAL_GPIO_INPEN));
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//
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// Initialize clkgen to output the selected clock.
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//
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am_hal_clkgen_clkout_enable(AM_HAL_CLKGEN_CLKOUT_CKSEL_LFRC_DIV2);
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//
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// Initialize LED 0 to on
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//
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am_devices_led_toggle(am_bsp_psLEDs, 0);
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iLEDcount = 1; // LED 1 is next
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//
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// Initialize loop variables
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//
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iRisingCount = RISING_EDGE_COUNT;
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bOldClkout = false;
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//
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// Loop forever tracking the rising edge of CLKOUT.
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//
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while (1)
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{
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//
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// Grab new clock output value and look for a change.
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//
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bNewClkout = am_hal_gpio_input_bit_read(AM_BSP_GPIO_CLKOUT_PIN);
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//
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// Look for any change.
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//
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if ( bOldClkout != bNewClkout )
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{
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//
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// OK a change occurred.
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//
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bOldClkout = bNewClkout;
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//
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// Was it rising or falling.
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//
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if ( bNewClkout )
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{
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//
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// It was rising so count them until time to act.
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//
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if (--iRisingCount < 0)
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{
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//
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// Act on the time out (walk the 4 LEDs)
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//
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am_devices_led_off(am_bsp_psLEDs, 0);
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am_devices_led_off(am_bsp_psLEDs, 1);
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am_devices_led_off(am_bsp_psLEDs, 2);
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am_devices_led_off(am_bsp_psLEDs, 3);
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am_devices_led_off(am_bsp_psLEDs, 4);
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am_devices_led_on(am_bsp_psLEDs, iLEDcount);
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iLEDcount++;
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iLEDcount %= 5;
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//
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// Reset the rising edge count.
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//
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iRisingCount = RISING_EDGE_COUNT;
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}
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}
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}
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}
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}
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