PWM

Overview

Pulse width modulation (PWM) is an efficient technique for controlling analog circuits using digital outputs from microprocessors.

The figure above shows a PWM waveform with a 100 Hz periodic frequency, featuring a 40% high-level duty cycle and 60% low-level duty cycle. By adjusting the high-level duty cycle value, the analog output level can be modified.

API description

tkl_pwm_init

OPERATE_RET tkl_pwm_init(TUYA_PWM_NUM_E ch_id, CONST TUYA_PWM_BASE_CFG_T *cfg);

• Features:

  • Initialize the specified PWM instance using the port number and basic configuration, and return the initialization result.

• Parameters:

  • ch_id: The channel ID.

  • cfg: The basic PWM configuration, including output polarity, duty cycle, and frequency.

    typedef struct {
        TUYA_PWM_POLARITY_E polarity;
        TUYA_PWM_COUNT_E    count_mode;
       //pulse duty cycle = duty / cycle; exp duty = 5000,cycle = 10000; pulse duty cycle = 50%
        UINT_T              duty;
        UINT_T              cycle;
        UINT_T              frequency;  // (bet: Hz)
    } TUYA_PWM_BASE_CFG_T;
    

  • polarity:

    Name	Definition
    TUYA_PWM_NEGATIVE	The PWM low active output.
    TUYA_PWM_POSITIVE	The PWM high active output.

  • count_mode: The counting mode, including TUYA_PWM_CNT_UP and TUYA_PWM_CNT_UP_AND_DOWN.

  • duty: The duty cycle, used with cycle. Output = duty ÷ cycle.

  • cycle: The cycle or granularity. Output = duty ÷ cycle.

  • frequency: The output frequency, in Hz.

• Return value:

  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_deinit

OPERATE_RET tkl_pwm_deinit(TUYA_PWM_NUM_E ch_id);

• Features:
  • Deinitialize the PWM.
  • This interface stops the ongoing transmission (if any) and releases the related software and hardware resources.
• Parameters:
  • ch_id: The channel ID.
• Return value:
  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_start

OPERATE_RET tkl_pwm_start(TUYA_PWM_NUM_E ch_id);

• Features:
  • Start the PWM.
• Parameters:
  • ch_id: The channel ID.
• Return value:
  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_stop

OPERATE_RET tkl_pwm_stop(TUYA_PWM_NUM_E ch_id);

• Features:
  • Stop the PWM.
• Parameters:
  • port: The port number.
• Return value:
  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_multichannel_start

OPERATE_RET tkl_pwm_multichannel_start(TUYA_PWM_NUM_E *ch_id, UINT8_T num);

• Features:
  • Start multi-channel PWM simultaneously. This interface is used for multi-channel combined output in scenarios with strict timing requirements.
• Parameters:
  • ch_id: The list of channel IDs in the form of an array.
  • num: The number of channels to be started.
• Return value:
  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_multichannel_stop

OPERATE_RET tkl_pwm_multichannel_stop(TUYA_PWM_NUM_E *ch_id, UINT8_T num);

• Features:

  • Stop multi-channel PWM simultaneously. This interface is used for multi-channel combined output in scenarios with strict timing requirements.

• Parameters:

  • ch_id: The list of channel IDs in the form of an array.
  • num: The number of channels to be stopped.

• Return value:

  • OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_info_set

OPERATE_RET tkl_pwm_info_set(TUYA_PWM_NUM_E ch_id, CONST TUYA_PWM_BASE_CFG_T *info);

• Features:
  • Set PWM configuration parameters. After PWM is started, the configuration can be modified dynamically, and then the PWM shall be started again.
• Parameters:
  • ch_id: The channel ID.
  • info: The basic PWM configuration, including output polarity, duty cycle, and frequency. The struct parameters are as described above.
• Return value:
  • An error message is returned on failure. OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_info_get

OPERATE_RET tkl_pwm_info_get(TUYA_PWM_NUM_E ch_id, TUYA_PWM_BASE_CFG_T *info);

• Features:
  • Get the PWM configuration information.
• Parameters:
  • ch_id: The channel ID.
  • info: The basic PWM configuration, including output polarity, duty cycle, and frequency. The struct parameters are as described above.
• Return value:
  • An error message is returned on failure. OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_cap_start

OPERATE_RET tkl_pwm_cap_start(TUYA_PWM_NUM_E ch_id, CONST TUYA_PWM_CAP_IRQ_T *cfg);

• Features:

  • Enable the PWM input capture mode.

• Parameters:

  • ch_id: The channel ID.

  • cfg: The PWM input capture configuration, as detailed below.

    • cap_mode:

      Name	Definition
      TUYA_PWM_CAPTURE_MODE_ONCE	Single trigger mode
      TUYA_PWM_CAPTURE_MODE_PERIOD	Multiple trigger mode

    • trigger_level:

      Name	Definition
      TUYA_PWM_NEGATIVE	The trigger signal is falling edge.
      TUYA_PWM_POSITIVE	The trigger signal is rising edge.

    • clk: The sampling clock of the captured signal.

    • cb: The callback function of the captured signal.

      typedef VOID_T (*TUYA_PWM_IRQ_CB)(TUYA_PWM_NUM_E port, TUYA_PWM_CAPTURE_DATA_T data, VOID_T *arg);
      

      typedef struct {
          UINT_T      cap_value;            /* Captured data */
          TUYA_PWM_POLARITY_E cap_edge;     /* Capture edge, TUYA_PWM_NEGATIVE:falling edge, TUYA_PWM_POSITIVE:rising edge */
      } TUYA_PWM_CAPTURE_DATA_T;
      

  • arg: The parameter of the callback function.

• Return value:

  • An error message is returned on failure. OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

tkl_pwm_cap_stop

OPERATE_RET tkl_pwm_cap_stop(TUYA_PWM_NUM_E ch_id);

• Features:

  • Disable the PWM input capture mode.

• Parameters:

  • ch_id: The channel ID.

• Return value:

  • An error message is returned on failure. OPRT_OK: Success.
  • For more information, see tuya_error_code.h.

Example

void tuya_pwm_test(void)
{
    OPERATE_RET ret;    
 	TUYA_PWM_BASE_CFG_T cfg = {.polarity = TUYA_PWM_POSITIVE,\
                         .duty = 1000,
                         .cycle = 10000,
                         .frequency = 1000};
    ret = tkl_pwm_init(TUYA_PWM_NUM_0, &cfg);
    if (ret != OPRT_OK) {
        //Fail
        return;
    }
    ret = tkl_pwm_start(TUYA_PWM_NUM_0);
    if (ret != OPRT_OK) {
        //Fail
        return;
    }
    tkl_system_delay(5000);
    ret = tkl_pwm_info_get(TUYA_PWM_NUM_0, &cfg);
    if (ret != OPRT_OK) {
        //Fail
        return;
    }
    if(cfg.duty !=5000){
        cfg.duty =5000;
    }
    ret = tkl_pwm_info_set(TUYA_PWM_NUM_0, &cfg);
    //Delay
    tkl_system_delay(5000);
    ret = tkl_pwm_stop(TUYA_PWM_NUM_0);
    if (ret != OPRT_OK) {
        //Fail
        return;
    }
    ret = tkl_pwm_deinit(TKL_PWM1_CH);
    if (ret != OPRT_OK) {
        //Fail
        return;
    }
}