Controlling the Digital Outputs of MBR3xxx CapSense® Express Devices - KBA90797

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Question: How do I control the digital outputs of the CY8CMBR3xxx family of CapSense devices?

 

Answer:

You can control and configure the digital outputs (general purpose outputs) of CY8CMBR3xxx CapSense® controllers in several ways.

The GPOs (General Purpose Outputs) can be configured to be directly driven by the corresponding sensor status. GPOs can also be controlled through the I2C register map value, where the host controller writes the output status of GPOs to the I2C register to control the GPO outputs.

Regardless of how the GPOs are controlled (either through the I2C register map or directly by the sensor status), the PWM feature can be enabled on GPOs. In this configuration, duty cycles for active and inactive states can be configured on the GPO. The active-state duty cycle represents the duty cycle of PWM when the input of the GPO (the register map value or sensor status) is in the active (ON) state. On the other hand, the inactive duty cycle represents the duty cycle of PWM when the input of the GPO (the register map value or sensor status) is in the inactive (OFF) state.

Regardless of these configurations, the GPO can be configured in active HIGH logic and active LOW logic.

In the active HIGH logic configuration, the GPO input state (the sensor status or register map value) is driven on the GPO. When the active LOW logic mode is selected, the GPO input state is inverted and driven on the GPO. If PWM is enabled, the active LOW logic mode inverts the duty cycle on the GPO output. This mode can be used to drive LEDs; you can choose active HIGH or LOW logic depending on how the LEDs are connected (in current sink or source mode).

In addition to these configurations, GPOs can be configured in open-drain (logic HIGH = HI-Z and Logic LOW= Ground) or strong drive (logic HIGH = VDD and logic LOW = Ground) modes.