MXT1664T3-ABESSQTP datasheet(67/98 Pages) MICROCHIP

67 / 98 page

MXT1664T3 2.0

 2018 Microchip Technology Inc.

DS40002054A-page 67

• To configure the device, a configuration parameter is written to the appropriate object. For example, writing to the

Power Configuration T7 configures the power consumption for the device and writing to the touchscreen Multiple

Touch Touchscreen T100 object sets up the touchscreen. Some objects are optional and need to be enabled

before use.

12.4

Reading from the Device

Status information is stored in the Message Processor T5 object. This object can be read to receive any status

information from the device. The following mechanisms provide an interrupt-style interface for reading messages in the

Message Processor T5 object:

• The CHG line is asserted whenever a new message is available in the Message Processor T5 object (see

Section 8.6 “CHG Line”). See Section 8.4 “Reading From the Device” for information on the format of the I2C read

operation.

• When using the USB interface, the interface provides an interrupt-driven interface that sends the messages

automatically (see Section 10.4.1.3 “Reading From the Device”).

• When using the HID-I2C interface, the interface provides an interrupt-driven interface that sends the messages

automatically (see Section 9.5.1.3 “Reading From the Device”)

Note that the host should always wait to be notified of messages. The host should not poll the device for messages.

IMPORTANT!

When the host issues any command within an object that results in a flash write to the device Non-

Volatile Memory (NVM), that object should have its CTRL RPTEN bit set to 1, if it has one. This

ensures that a message from the object writing to the NVM is generated at the completion of the

process and an assertion of the CHG line is executed.

The host must also ensure that the assertion of the CHG line refers to the expected object report

ID before asserting the RESET line to perform a reset. Failure to follow this guidance may result in

a corruption of device configuration area and the generation of a CFGERR.

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