BU21028FV-M Datasheet, PDF (16/36 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21028FV-M
CF=0x5 (0101) Calibration timing chart
HOST CALIB
(CF=0x5)
INT
BU21029
Detecting
touch
tConv1
tConv1
Sample and Conversion
for X coordinate
Sample and Conversion
for Y coordinate
tCalib
Calibrate
parameters
tConv1
tConv1
Sample and Conversion
for X coordinate
Sample and Conversion
for Y coordinate
Read
Status
tCalib
Calibrate
parameters
Detecting
touch
Figure 5. Calibration Flow
tPON
= 710us
tDLY1
= 1.5us
tADC
= 18us
tDLY2
= 1.0us
tTIME_ST_ADC = register (addr.0x2)
tSMPL
= register (addr.0x1)
tConv1
tCalib
= tPON + tDLY1 + (tTIME_ST_ADC + (tADC * tSMPL) * 2 + tDLY2)
= 1 internal clock
(*1) Even if the part with dashed lines is not performed, read status does not influence the operation.
(*2) Except the first one, tPON(s) is always zero.
Sensing timing chart (command mode)
HOST
INT
Turn On
X+ and X-
Drivers
(CF=0x8)
BU21029
Detecting
touch
SCAN X
(CF=0xC)
tConv1
Waiting for
Sample and Conversion
scan command
for X coordinate
Read
result of
SCAN X
Turn On
Y+ and Y-
Drivers
(CF=0x9)
SCAN Y
(CF=0xD)
tConv1
Detecting
touch
Waiting for Sample and Conversion
scan command
for Y coordinate
Read
result of
SCAN Y
Detecting
touch
Figure 6. Touch Screen Scan Flow 1 (X and Y scan)
HOST
INT
Turn On
X+ and Y-
Drivers
(CF=0xA)
BU21029
Detecting
touch
SCAN Z
(CF=0xE)
Waiting for
scan command
tConv2
Sample and Conversion
for Z1 coordinate
tConv3
Sample and Conversion
for Z2 coordinate
Read
result of
SCAN Z1
Read
result of
SCAN Z2
Detecting
touch
Figure 7. Touch screen scan flow 2 (Z1 and Z2 scan)
tPON
= 710us
tDLY1
= 1.5us
tADC
= 18us
tDLY2
= 1.0us
tTIME_ST_ADC = register (addr.0x2)
tSMPL
= register (addr.0x1)
tConv1
tConv2
tConv3
= tPON + tDLY1 + (tTIME_ST_ADC + (tADC * tSMPL) * 2 + tDLY2)
= tPON + tDLY1 + tTIME_ST_ADC + (tADC * tSMPL) + tDLY2
= tDLY1 + (tADC * tSMPL) + tDLY2
(*1) Time is calculated with the oscillating frequency of the internal OSC at 8MHz.
(*2) In case PDM=1, tPON(s) is set to zero except for the first one.
(*3) The dashed part is required only when apply time set for a panel is more than TIME_ST_ADC.
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TSZ22111 • 15 • 001
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TSZ02201-0L5L0F300720-1-2
27.May.2016 Rev.002