BU21021GUL Datasheet, PDF (4/13 Pages) Rohm – 4-wire resistive Touch Screen Controller

BU21021GUL
Datasheet
●Overview
BU21021GUL is a resistive touch screen controller, which is capable of detecting 2 points touch with a legacy 4-wire
resistive touch screen. It is composed of 32-bit CPU, 12-bit SAR A/D converter, clock oscillator, and voltage regulators
power supply, and operates at a single power supply ranging from 2.7 to 3.6V. BU21021GUL is capable of detecting X/Y
coordinates, touch pressure in 1 point detection mode, and a pair of X/Y coordinates in 2 point detection mode.
It is also capable of recognizing multiple finger gestures from coordinate data variation and notifying to host with gesture
detection flags respectively.BU21021GUL employs embedded CPU for noise filtering, coordinate calculation, gesture
detection and other signal processing required on a chip.
BU21021GUL senses panel terminal voltages periodically, filters noise, then calculates coordinates in its operation mode.
Host will be noticed by a interrupt signal (INT) when resister values are updated.
1 point detection
Touch detection and touch pressure detection are processed on chip, and BU21021GUL operates as a legacy
resistive touch controller employing 4-wire resistive touch screen.
BU21021GUL has 2 point touch detection function, which prevents itself from common misdetection of single
‘midpoint’ coordinate output.
2 points detection
2 point detection is held by monitoring electric condition of a touch sensor and calculating coordinates on each axis.
The process is different from legacy 1 point touch detection, therefore BU21021GUL requires setup of panel parameter
in advance.
BU21021GUL automatically detects ether 1 point or 2 points touch input.
Gesture detection
BU21021GUL is able to detect 1 point flick gesture for 4 directions and 2 point ZOOM IN/OUT, PINCH/SPREAD and
rotate gestures respectively. Gesture detection events are reported to host as detection flags and interrupt. Each of
gesture detection sensitivities can be set as register parameters respectively.
(Note) Gesture flags only repot its events. Operation speed and movement have to be calculate on host using
coordinate data.
Auto power on / off function
Auto power off function will power off to sleep condition in order to reduce power consumption when no touch input is
detected. BU21021GUL will automatically change to operation state when touch event is detected in sleep state.
This function is able to be enabled / disabled, and threshold level of sleep state transition is able to be set by registers.
Host interface
BU21021GUL works as slave device of HOST MCU connected 2-wire serial bus or 4-wire SPI.
It is selectable by IFSEL pin condition.
(IFSEL=GND：4-wire SPI、IFSEL=VDD：2-wire serial bus)
EEPROM
Firmware has to be downloaded on BU21021GUL in order to realize these functions. The file size of firmware is 16kB
(16384 bytes). A "HOST interface" and "external EEPROM" can be chosen as the download method.
DVDD external supply setup
In the case there exists 1.8V power supply on application system, the external 1.8V supply can be applicable to DVDD
in order to reduce sleep power consumption to 10uA.
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TSZ22111・15・001
4/10
TSZ02201-0Y1Y0F300060-1-2
19.Jun.2012 Rev.001