main.c

/******************************************************************************
* File Name:   main.c
*
* Description: This is the source code for the PDM PCM Example
*              for ModusToolbox.
*
* Related Document: See README.md 
*
*
*******************************************************************************
* Copyright 2021-2022, Cypress Semiconductor Corporation (an Infineon company) or
* an affiliate of Cypress Semiconductor Corporation.  All rights reserved.
*
* This software, including source code, documentation and related
* materials ("Software") is owned by Cypress Semiconductor Corporation
* or one of its affiliates ("Cypress") and is protected by and subject to
* worldwide patent protection (United States and foreign),
* United States copyright laws and international treaty provisions.
* Therefore, you may use this Software only as provided in the license
* agreement accompanying the software package from which you
* obtained this Software ("EULA").
* If no EULA applies, Cypress hereby grants you a personal, non-exclusive,
* non-transferable license to copy, modify, and compile the Software
* source code solely for use in connection with Cypress's
* integrated circuit products.  Any reproduction, modification, translation,
* compilation, or representation of this Software except as specified
* above is prohibited without the express written permission of Cypress.
*
* Disclaimer: THIS SOFTWARE IS PROVIDED AS-IS, WITH NO WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, NONINFRINGEMENT, IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress
* reserves the right to make changes to the Software without notice. Cypress
* does not assume any liability arising out of the application or use of the
* Software or any product or circuit described in the Software. Cypress does
* not authorize its products for use in any products where a malfunction or
* failure of the Cypress product may reasonably be expected to result in
* significant property damage, injury or death ("High Risk Product"). By
* including Cypress's product in a High Risk Product, the manufacturer
* of such system or application assumes all risk of such use and in doing
* so agrees to indemnify Cypress against all liability.
*******************************************************************************/

#include "cyhal.h"
#include "cybsp.h"
#include "cy_retarget_io.h"

#include "stdlib.h"

/*******************************************************************************
* Macros
********************************************************************************/
/* Define how many samples in a frame */
#define FRAME_SIZE                  (1024)
/* Noise threshold hysteresis */
#define THRESHOLD_HYSTERESIS        3u
/* Volume ratio for noise and print purposes */
#define VOLUME_RATIO                (4*FRAME_SIZE)
/* Desired sample rate. Typical values: 8/16/22.05/32/44.1/48kHz */
#define SAMPLE_RATE_HZ              8000u
/* Decimation Rate of the PDM/PCM block. Typical value is 64 */
#define DECIMATION_RATE             64u
/* Audio Subsystem Clock. Typical values depends on the desire sample rate:
- 8/16/48kHz    : 24.576 MHz
- 22.05/44.1kHz : 22.579 MHz */
#define AUDIO_SYS_CLOCK_HZ          24576000u
/* PDM/PCM Pins */
#define PDM_DATA                    P10_5
#define PDM_CLK                     P10_4

/*******************************************************************************
* Function Prototypes
********************************************************************************/
void button_isr_handler(void *arg, cyhal_gpio_event_t event);
void pdm_pcm_isr_handler(void *arg, cyhal_pdm_pcm_event_t event);
void clock_init(void);

/*******************************************************************************
* Global Variables
********************************************************************************/
/* Interrupt flags */
volatile bool button_flag = false;
volatile bool pdm_pcm_flag = true;

/* Volume variables */
uint32_t volume = 0;
uint32_t noise_threshold = THRESHOLD_HYSTERESIS;

/* HAL Object */
cyhal_pdm_pcm_t pdm_pcm;
cyhal_clock_t   audio_clock;
cyhal_clock_t   pll_clock;

/* HAL Config */
const cyhal_pdm_pcm_cfg_t pdm_pcm_cfg = 
{
    .sample_rate     = SAMPLE_RATE_HZ,
    .decimation_rate = DECIMATION_RATE,
    .mode            = CYHAL_PDM_PCM_MODE_STEREO, 
    .word_length     = 16,  /* bits */
    .left_gain       = 0,   /* dB */
    .right_gain      = 0,   /* dB */
};

/*This structure is used to initialize callback*/
cyhal_gpio_callback_data_t cb_data =
    {
        .callback = button_isr_handler,
        .callback_arg = NULL
 };


/*******************************************************************************
* Function Name: main
********************************************************************************
* Summary:
* The main function for Cortex-M4 CPU does the following:
*  Initialization:
*  - Initializes all the hardware blocks
*  Do forever loop:
*  - Check if PDM/PCM flag is set. If yes, report the current volume
*  - Update the LED status based on the volume and the noise threshold
*  - Check if the User Button was pressed. If yes, reset the noise threshold
*
* Parameters:
*  void
*
* Return:
*  int
*
*******************************************************************************/
int main(void)
{
    cy_rslt_t result;
    int16_t  audio_frame[FRAME_SIZE] = {0};

    /* Initialize the device and board peripherals */
    result = cybsp_init() ;
    if (result != CY_RSLT_SUCCESS)
    {
        CY_ASSERT(0);
    }

    /* Enable global interrupts */
    __enable_irq();

    /* Init the clocks */
    clock_init();

    /* Initialize retarget-io to use the debug UART port */
    cy_retarget_io_init(CYBSP_DEBUG_UART_TX, CYBSP_DEBUG_UART_RX, CY_RETARGET_IO_BAUDRATE);

    /* Initialize the User LED */
    cyhal_gpio_init(CYBSP_USER_LED, CYHAL_GPIO_DIR_OUTPUT, CYHAL_GPIO_DRIVE_STRONG, CYBSP_LED_STATE_OFF);

    /* Initialize the User Button */
    cyhal_gpio_init(CYBSP_USER_BTN, CYHAL_GPIO_DIR_INPUT, CYHAL_GPIO_DRIVE_PULLUP, CYBSP_BTN_OFF);
    cyhal_gpio_enable_event(CYBSP_USER_BTN, CYHAL_GPIO_IRQ_FALL, CYHAL_ISR_PRIORITY_DEFAULT, true);
    cyhal_gpio_register_callback(CYBSP_USER_BTN, &cb_data);

    /* Initialize the PDM/PCM block */
    cyhal_pdm_pcm_init(&pdm_pcm, PDM_DATA, PDM_CLK, &audio_clock, &pdm_pcm_cfg);
    cyhal_pdm_pcm_register_callback(&pdm_pcm, pdm_pcm_isr_handler, NULL);
    cyhal_pdm_pcm_enable_event(&pdm_pcm, CYHAL_PDM_PCM_ASYNC_COMPLETE, CYHAL_ISR_PRIORITY_DEFAULT, true);
    cyhal_pdm_pcm_start(&pdm_pcm);
    
    /* \x1b[2J\x1b[;H - ANSI ESC sequence for clear screen */
    printf("\x1b[2J\x1b[;H");

    printf("****************** \
    PDM/PCM Example \
    ****************** \r\n\n");

    for(;;)
    {
        /* Check if any microphone has data to process */
        if (pdm_pcm_flag)
        {
            /* Clear the PDM/PCM flag */
            pdm_pcm_flag = 0;

            /* Reset the volume */
            volume = 0;

            /* Calculate the volume by summing the absolute value of all the 
             * audio data from a frame */
            for (uint32_t index = 0; index < FRAME_SIZE; index++)
            {
                volume += abs(audio_frame[index]);
            }

            /* Prepare line to report the volume */
            printf("\n\r");

            /* Report the volume */
            for (uint32_t index = 0; index < (volume/VOLUME_RATIO); index++)
            {
                printf("-");
            }

            /* Turn ON the LED when the volume is higher than the threshold */
            if ((volume/VOLUME_RATIO) > noise_threshold)
            {
                cyhal_gpio_write((cyhal_gpio_t) CYBSP_USER_LED, CYBSP_LED_STATE_ON);
            }
            else
            {
                cyhal_gpio_write((cyhal_gpio_t) CYBSP_USER_LED, CYBSP_LED_STATE_OFF);
            }

            /* Setup to read the next frame */
            cyhal_pdm_pcm_read_async(&pdm_pcm, audio_frame, FRAME_SIZE);
        }

        /* Reset the noise threshold if User Button is pressed */
        if (button_flag)
        {
            /* Reset button flag */
            button_flag = false;

            /* Get the current volume and add a hysteresis as the new threshold */
            noise_threshold = (volume/VOLUME_RATIO) + THRESHOLD_HYSTERESIS;

            /* Report the new noise threshold over UART */
            printf("\n\rNoise threshold: %lu\n\r", (unsigned long) noise_threshold);
        }

        cyhal_syspm_sleep();

    }
}

/*******************************************************************************
* Function Name: button_isr_handler
********************************************************************************
* Summary:
*  Button ISR handler. Set a flag to be processed in the main loop.
*
* Parameters:
*  arg: not used
*  event: event that occurred
*
*******************************************************************************/
void button_isr_handler(void *arg, cyhal_gpio_event_t event)
{
    (void) arg;
    (void) event;

    button_flag = true;
}

/*******************************************************************************
* Function Name: pdm_pcm_isr_handler
********************************************************************************
* Summary:
*  PDM/PCM ISR handler. Set a flag to be processed in the main loop.
*
* Parameters:
*  arg: not used
*  event: event that occurred
*
*******************************************************************************/
void pdm_pcm_isr_handler(void *arg, cyhal_pdm_pcm_event_t event)
{
    (void) arg;
    (void) event;

    pdm_pcm_flag = true;
}

/*******************************************************************************
* Function Name: clock_init
********************************************************************************
* Summary:
*  Initialize the clocks in the system.
*
*******************************************************************************/
void clock_init(void)
{
    /* Initialize the PLL */
    cyhal_clock_reserve(&pll_clock, &CYHAL_CLOCK_PLL[0]);
    cyhal_clock_set_frequency(&pll_clock, AUDIO_SYS_CLOCK_HZ, NULL);
    cyhal_clock_set_enabled(&pll_clock, true, true);

    /* Initialize the audio subsystem clock (CLK_HF[1]) 
     * The CLK_HF[1] is the root clock for the I2S and PDM/PCM blocks */
    cyhal_clock_reserve(&audio_clock, &CYHAL_CLOCK_HF[1]);

    /* Source the audio subsystem clock from PLL */
    cyhal_clock_set_source(&audio_clock, &pll_clock);
    cyhal_clock_set_enabled(&audio_clock, true, true);
}

/* [] END OF FILE */