BU21028FV-M Datasheet, PDF (14/36 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21028FV-M
Control Flow Chart
BU21028FV-M has two operation modes, the command mode, wherein the device operates under the control of the host
processor, and auto mode, wherein the device operates by automatic control.
In order to use two-point detection, it is necessary to calibrate the circuit for this function by setting the correct state of
registers for panel perimeters (register Addr.0x3, 0x4). Calibration is performed by transmitting the command CF=0101 from
the host processor. Take note that each register should be initialized after power on. Moreover, for two-point detection, the
interrupt signal from the IC should be enabled after performing parameter calibration.
Power-on Sequence flow chart
Start
White box: Control flow
Charcoal gray box: Divergence by the use function
Light gray box: For periodic calibration
Power supply
Reset release
(RSTB = H)
Wait internal reset release
(min. 1ms）
Initialize register
Use 2-points detection
No
Count = 0
(For periodic calibration)
Yes
Check INT pin or read status register
Touch detection
No
Yes
Wait
Use only single touch detection
Send calibration command
(CF = 0x5)
Wait for finish calibration by below way
・Check INT pin
・Check register(CALIB_DONE)
(page=0, addr.=0x0D bit1)
・Wait for more than 10ms
　　
Use Auto mode
No
Yes
Send scan_XYZ command
(CF = 0x0)
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TSZ22111 • 15 • 001
Start timer
(For periodic calibration)
Disable interrupt MASK on HOST
SCAN status
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TSZ02201-0L5L0F300720-1-2
27.May.2016 Rev.002