PDEC Asynchronous Driver

In the Position Decoder (PDEC) asynchronous driver, a callback function can be registered in the driver by the application, and the callback function will be triggered when axis position changed.

The driver pdec_async_read_position function will attempt to read the required position results of the axis.

Parent topic: Position Decoder Driver

Summary of the API's Functional Features

The API provides functions to:

  • Initialize and deinitialize the driver and associated hardware

  • Hookup callback handlers on position changed done and IRQ events

  • Enable or disable PDEC module

  • Read back axis position result

Summary of Configuration Options

Below is a list of the main PDEC parameters that can be configured in START. Many of these parameters are used by the adc_async_init function when initializing the driver and underlying hardware.

  • Select whether phase A, B, or index invert is to be used

  • Select whether phase A or B should be swapped

  • Which clock source and prescaler the PDEC uses

  • Which configuration the PDEC uses

  • Which events the PDEC interrupt uses

  • Run in Standby or Debug mode

Driver Implementation Description

After PDEC hardware initialization, thee application can register the callback function for axis position changed and IRQ events by pdec_async_register_callback.

Example of Usage

The following shows a simple example of using the PDEC. The PDEC must have been initialized by pdec_async_init. This initialization will configure the operation of the PDEC, such as input pins, prescaler value, PDEC configuration, and interrupt configuration, etc.

The example registers a callback function for comparison ready and enables the PDEC, and read back the result of the axis position changed.

          static void position_cb_POSITION_DECODER_0(struct pdec_async_descriptor *const descr, uint8_t ch)
          {
              uint16_t count;
              count = pdec_async_read_position(descr, ch);
          }
          static void irq_handler_cb_POSITION_DECODER_0(struct pdec_async_descriptor *const descr,
                                                        enum pdec_async_callback_type type, uint8_t ch)
          {
          }
          /**
           * Example of using POSITION_DECODER_0.
           */
          void POSITION_DECODER_0_example(void)
          {
              pdec_async_register_callback(
                  &POSITION_DECODER_0, PDEC_ASYNC_POS_CHANGED_CB, (FUNC_PTR)position_cb_POSITION_DECODER_0);
              pdec_async_register_callback(&POSITION_DECODER_0, PDEC_ASYNC_IRQ_CB, (FUNC_PTR)irq_handler_cb_POSITION_DECODER_0);
              pdec_async_enable(&POSITION_DECODER_0);
          }

Dependencies

  • The PDEC peripheral and its related I/O lines and clocks

  • The NVIC must be configured so that PDEC interrupt requests are periodically serviced