IMX8 QuadMax TPM module

[AhmedMobarez]

Hello everyone,

I'm an NXP newbie and just started testing some example code from the NXP SDK 2.9 for IMX8QM, I'm trying to generate simple PWM using the TPM example code, the code runs well and generates a PWM signal down to 10Khz, if I put a lower frequency I just get low on the signal.

I change the frequency in the 5th parameter of the following function:

TPM_SetupPwm(BOARD_TPM_BASEADDR, &tpmParam, 1U, kTPM_EdgeAlignedPwm, 100U, TPM_SOURCE_CLOCK);

at 10,000U or more it works perfectly, at 100 or 1000 the output is always low, I didn't find any minimum value mentioned anywhere so not sure what's wrong, changing the prescaler didn't help also, this is the full code for reference:

/*
 * Copyright (c) 2015, Freescale Semiconductor, Inc.
 * Copyright 2016-2017 NXP
 * All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "fsl_debug_console.h"
#include "pin_mux.h"
#include "clock_config.h"
#include "board.h"
#include "fsl_tpm.h"

/*******************************************************************************
 * Definitions
 ******************************************************************************/
/* define instance */
#define BOARD_TPM_BASEADDR CM4_0__TPM
#define BOARD_TPM_CHANNEL  0U

/* Interrupt to enable and flag to read; depends on the TPM channel used */
#define TPM_CHANNEL_INTERRUPT_ENABLE kTPM_Chnl0InterruptEnable
#define TPM_CHANNEL_FLAG             kTPM_Chnl0Flag

/* Interrupt number and interrupt handler for the TPM instance used */
#define TPM_INTERRUPT_NUMBER M4_0_TPM_IRQn
#define TPM_LED_HANDLER      M4_0_TPM_IRQHandler

/* Get source clock for TPM driver */
#define TPM_SOURCE_CLOCK (CLOCK_GetIpFreq(kCLOCK_M4_0_Tpm))

/*******************************************************************************
 * Prototypes
 ******************************************************************************/
/*!
 * @brief delay a while.
 */
void delay(void);

/*******************************************************************************
 * Variables
 ******************************************************************************/
volatile bool brightnessUp        = true; /* Indicate LED is brighter or dimmer */
volatile uint8_t updatedDutycycle = 40U;
volatile uint8_t getCharValue     = 0U;

/*******************************************************************************
 * Code
 ******************************************************************************/
/*!
 * @brief Main function
 */
int main(void)
{
    tpm_config_t tpmInfo;
    tpm_chnl_pwm_signal_param_t tpmParam;

#ifndef TPM_LED_ON_LEVEL
#define TPM_LED_ON_LEVEL kTPM_HighTrue
#endif

    /* Configure tpm params with frequency 24kHZ */
    tpmParam.chnlNumber       = (tpm_chnl_t)BOARD_TPM_CHANNEL;
    tpmParam.level            = TPM_LED_ON_LEVEL;
    tpmParam.dutyCyclePercent = updatedDutycycle;

    /* Board pin, clock, debug console init */
    sc_ipc_t ipc;

    ipc = BOARD_InitRpc();

    BOARD_InitPins(ipc);
    BOARD_BootClockRUN();
    BOARD_InitMemory();
    BOARD_InitDebugConsole();

    /* Power on peripherals. */
    if (sc_pm_set_resource_power_mode(ipc, SC_R_M4_0_TPM, SC_PM_PW_MODE_ON) != SC_ERR_NONE)
    {
        PRINTF("Error: Failed to power on TPM\r\n");
    }

    /* Set peripheral's clock */
    if (CLOCK_SetIpFreq(kCLOCK_M4_0_Tpm, SC_66MHZ) == 0)
    {
        PRINTF("Error: Failed to set TPM frequency\r\n");
    }

    /* Print a note to terminal */
    PRINTF("\r\nTPM example to output center-aligned PWM signal\r\n");
    PRINTF(
        "\r\nIf an LED is connected to the TPM pin, you will see a change in LED brightness if you enter different "
        "values");
    PRINTF("\r\nIf no LED is connected to the TPM pin, then probe the signal using an oscilloscope");

    TPM_GetDefaultConfig(&tpmInfo);
    tpmInfo.prescale = kTPM_Prescale_Divide_128;

    /* Initialize TPM module */
    TPM_Init(BOARD_TPM_BASEADDR, &tpmInfo);

    TPM_SetupPwm(BOARD_TPM_BASEADDR, &tpmParam, 1U, kTPM_EdgeAlignedPwm, 100U, TPM_SOURCE_CLOCK);

    TPM_StartTimer(BOARD_TPM_BASEADDR, kTPM_SystemClock);

    while (1)
    {

    }
}

[jimmychan]

You could read the fsl_tmp.c in the drivers folder.