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Touch Sensor

Introduction

The touch sensor system consists of a protective cover layer, touch electrodes, an insulating substrate, and wiring. The protective cover layer is at the topmost layer, with electrodes and wiring on the insulating substrate. Touching the cover layer causes capacitance changes. Based on these changes, it can be determined whether the touch is a valid touch action.

Function List

Initialize - Initialize the touch sensor driver.

Set Threshold - Set the threshold for the touch sensor.

Get Threshold - Get the threshold of the touch sensor.

Read Count - Read the count value of the touch sensor.

Start Sensor - Start the touch sensor.

Stop Sensor - Stop the touch sensor.

Register Callback - Register a callback function for the touch sensor.

Feature Overview

W803 integrates a touch sensor module that scans the status of each touch button in sequence at regular intervals when working. It counts and records the status of each button within the set time window. If it exceeds the set threshold, the button is considered to be touched, and application processing is done through polling or interrupts.

The current software adjustable parameter is only the touch threshold (adjustable range: 0-127). It can be adjusted to a most suitable value according to the actual environment.

W803 has a total of 10 available TOUCH touch pins and two control pins. The relationship of the touch sensor pins is shown in the table below.

Touch Sensor Number (Name)	Pin Number	Pin Name	Pin Multiplex Function	Pin Attribute
TOUCH3	PIN_NUM_16	PB0	OPT7	float/input
TOUCH4	PIN_NUM_17	PB1	OPT7	float/input
TOUCH5	PIN_NUM_18	PB2	OPT7	float/input
TOUCH6	PIN_NUM_19	PB3	OPT7	float/input
TOUCH7	PIN_NUM_20	PB4	OPT7	float/input
TOUCH8	PIN_NUM_21	PB5	OPT7	float/input
TOUCH9	PIN_NUM_22	PB6	OPT7	float/input
TOUCH10	PIN_NUM_23	PB7	OPT7	float/input
TOUCH11	PIN_NUM_24	PB8	OPT7	float/input
TOUCH12	PIN_NUM_25	PB9	OPT7	float/input
CMOD	PIN_NUM_12	PA12	OPT7	float/input
CDC	PIN_NUM_14	PA14	OPT7	float/input

The touch sensor circuit design reference is shown in the table below.

The touch sensor can be combined in matrix or slider formats to cover larger touch areas and more touch points.

Main Features

Initialize Touch Sensor

To use the touch sensor, you need to call the wm_drv_touch_sensor_init() function to initialize the driver. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

Set Threshold

To set the threshold of the touch sensor, you can call the wm_drv_touch_sensor_set_threshold() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

wm_drv_touch_sensor_set_threshold(touch_dev, WM_TOUCH_SENSOR_NUM_1, 100);

Get Threshold

To get the threshold of the touch sensor, you can call the wm_drv_touch_sensor_get_threshold() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

uint32_t threshold;
wm_drv_touch_sensor_get_threshold(touch_dev, WM_TOUCH_SENSOR_NUM_1, &threshold);

Read Count

To read the count value of the touch sensor, you can call the wm_drv_touch_sensor_read_countnum() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

uint32_t countnum;
wm_drv_touch_sensor_read_countnum(touch_dev, 0, &countnum);

Start Sensor

To start the touch sensor, you can call the wm_drv_touch_sensor_start() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

wm_drv_touch_sensor_start(touch_dev, WM_TOUCH_SENSOR_NUM_1);

Stop Sensor

To stop the touch sensor, you can call the wm_drv_touch_sensor_stop() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

wm_drv_touch_sensor_stop(touch_dev, WM_TOUCH_SENSOR_NUM_1);

Register Callback

To register a callback function for the touch sensor, you can call the wm_drv_touch_sensor_register_callback() function. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

void touch_callback(wm_touch_sensor_num_t touch_num, void *priv)
{
}

wm_drv_touch_sensor_register_callback(touch_dev, WM_TOUCH_SENSOR_NUM_1, touch_callback, NULL);

Deinitialize Touch Sensor

When the touch sensor is no longer needed, you can call the wm_drv_touch_sensor_deinit() function to deinitialize the driver and release resources. Example:
wm_device_t *touch_dev;
touch_dev = wm_drv_touch_sensor_init("touch_sensor");

wm_drv_touch_sensor_deinit(touch_dev);

Application Examples

For basic examples of using the touch sensor, please refer to: examples/peripheral/touch_sensor

API Reference

Touch Button touch button

Touch Slider (Not yet implemented)

Touch Matrix Button (Not yet implemented)