CST816S

An Arduino library for the CST816S capacitive touch screen IC

Auto Sleep Control

Auto Sleep is referred to as Standby Mode in this Waveshare document. Disabling of auto sleep or auto standby will keep the touch display in Dynamic mode. This will improve responsiveness, at the cost of about ~1.6mA.

By default, auto sleep is enabled with a timeout of 2 seconds. The following functions allow you to manage auto sleep behavior:

• void disable_auto_sleep();
  Disables auto sleep, keeping the device active indefinitely.

• void enable_auto_sleep();
  Re-enables auto sleep with the current timeout (default is 2 seconds).

• void set_auto_sleep_time(int seconds);
  Sets the auto sleep timeout in seconds (1-255).
  Example: set_auto_sleep_time(10); sets a 10-second timeout.

User-Provided Interrupt

The CST816S library allows you to attach a custom interrupt function to handle touch events according to your application's needs. By providing a user-defined interrupt, you can trigger specific actions upon touch events, such as waking the device from a low-power state, checking gestures, or executing custom logic without constantly polling the device.

Feature Highlights:

• Custom Event Handling: Define and attach a user function that executes on each touch interrupt, allowing immediate responses to touch events.
• Power Management: Ideal for applications needing to manage power, such as waking from sleep modes, as the interrupt triggers only on touch.

• Gesture-Based Logic: Use the interrupt to wake, then analyze gestures to decide on further actions, enabling efficient and gesture-responsive behavior.

  Register Information

  The following information was extracted from this document provided by Waveshare.

  Register Name	Address	Bit Description	Default Value	Configuration Options
  GestureID	0x01	Gesture code for detected gestures	N/A	- 0x00: None - 0x01: Slide Up - 0x02: Slide Down - 0x03: Slide Left - 0x04: Slide Right - 0x05: Single Click - 0x0B: Double Click - 0x0C: Long Press
  FingerNum	0x02	Number of fingers detected	N/A	- 0: No finger - 1: One finger
  XposH	0x03	High 4 bits of X coordinate	N/A	-
  XposL	0x04	Low 8 bits of X coordinate	N/A	-
  YposH	0x05	High 4 bits of Y coordinate	N/A	-
  YposL	0x06	Low 8 bits of Y coordinate	N/A	-
  BPC0H	0xB0	High 8 bits of BPC0 value	N/A	-
  BPC0L	0xB1	Low 8 bits of BPC0 value	N/A	-
  BPC1H	0xB2	High 8 bits of BPC1 value	N/A	-
  BPC1L	0xB3	Low 8 bits of BPC1 value	N/A	-
  ChipID	0xA7	Chip model identifier	N/A	-
  ProjID	0xA8	Project number	N/A	-
  FwVersion	0xA9	Firmware version number	N/A	-
  MotionMask	0xEC	Enable continuous gesture actions and double-click	0x00	- Bit 0: EnDClick (enable double-click) - Bit 1: EnConUD (enable continuous up/down swipe) - Bit 2: EnConLR (enable continuous left/right swipe)
  IrqPluseWidth	0xED	Interrupt pulse width (0.1 ms units)	10	1-200
  NorScanPer	0xEE	Normal scan period (10 ms units)	1	1-30
  MotionSlAngle	0xEF	Gesture detection sliding angle control (Angle = tan(c) * 10, where c is the angle relative to the positive X-axis)	N/A	-
  LpScanRaw1H	0xF0	High 8 bits of low-power scan channel 1 reference	N/A	-
  LpScanRaw1L	0xF1	Low 8 bits of low-power scan channel 1 reference	N/A	-
  LpScanRaw2H	0xF2	High 8 bits of low-power scan channel 2 reference	N/A	-
  LpScanRaw2L	0xF3	Low 8 bits of low-power scan channel 2 reference	N/A	-
  LpAutoWakeTime	0xF4	Low-power mode auto recalibration interval (in minutes)	5 minutes	1-5 minutes
  LpScanTH	0xF5	Low-power scan wake threshold. The smaller the value, the more sensitive it is.	48	1-255
  LpScanWin	0xF6	Low-power scan range. The larger the value, the more sensitive it is, but power consumption increases.	3	0-3
  LpScanFreq	0xF7	Low-power scan frequency. The smaller the value, the more sensitive it is.	7	1-255
  LpScanIdac	0xF8	Low-power scan current. The smaller the value, the more sensitive it is.	N/A	1-255
  AutoSleepTime	0xF9	Time in seconds before entering standby mode after inactivity	2 seconds	1-255 seconds
  IrqCtl	0xFA	Control of interrupt behavior	N/A	- Bit 7: EnTest (Enable test, periodically sends low pulses) - Bit 6: EnTouch (Sends low pulse on touch detection) - Bit 5: EnChange (Sends low pulse on touch state change) - Bit 4: EnMotion (Sends low pulse on gesture detection) - Bit 0: OnceWLP (Sends one low pulse on long press)
  AutoReset	0xFB	Auto-reset time after detecting touch with no valid gesture	5 seconds	- 0: Disable - 1-5: Time in seconds before auto-reset
  LongPressTime	0xFC	Time (in seconds) for a long press to trigger reset	10 seconds	- 0: Disable - 1-10: Long press duration in seconds
  IOCtl	0xFD	IO control settings including soft reset and power options	N/A	- Bit 2: SOFT_RST (0: Disable soft reset, 1: Enable soft reset) - Bit 1: IIC_OD (0: Pull-up resistor, 1: Open-drain) - Bit 0: En1v8 (0: VDD, 1: 1.8V)
  DisAutoSleep	0xFE	Disable automatic entry into low-power mode	0 (enabled)	- 0: Enable auto sleep - Non-zero: Disable auto sleep