A31T214/ 216 – The water tolerance function for washing machines

As a Cortex M0+ based MCU, the A31T214/ 216 is used for the User Interface (i.e. Touch and Display) of home appliances. This product is equipped with the Water Tolerance function that prevents Touch malfunction due to unintentional moisture, particularly targeting washing machines.

The Water Tolerance function in the A31T214/ 216 is largely divided into 2 types as follows:

▶   MESH-SHLD: It prevents the Touch malfunction due to water droplets formed on and around the Touch Pad.

▶   CH-SHLD: It prevents the Touch malfunction due to water droplets formed between Touch Pads.

Users can easily implement the Water Tolerance function using the libraries that we provide.

▶   TS_Set_Shield(CH_SHIELD_EN, MESH_SHIELD_EN)

The first parameter in the above function selects whether to use the CH-SHLD (CH_SHIELD_EN/ CH_SHIELD_DIS), and the second parameter selects whether to use the MESH-SHLD (MESH_SHIELD_EN/ MESH_SHIELD_DIS).

The CS23 is a channel assigned for the MESH-SHLD. It can be used as a normal Touch channel if not used for the MESH-SHLD function.

In Figure 1, we can check the difference between when the Water Tolerance function is applied and when the Water Tolerance function is not applied.

[Figure 1. Touch screen with and without Water Tolerance Function]