AR1000 Datasheet, PDF (16/37 Pages) Microchip Technology – Resistive Touch Screen Controller

7.12 Configuration Registers
The Configuration Registers allow application specific customization of the controller. The default values have
been optimized for most applications and are automatically used, unless you choose to change them.
Unique sensors and/or product applications may benefit from adjustment of configuration registers.
The factory default settings for the Configuration registers can be recovered by writing a value of 0xFF to address
0x00 of the EEPROM, then cycling power.
Register Name
TouchThreshold
SensitivityFilter
SamplingFast
SamplingSlow
AccuracyFilterFast
AccuracyFilterSlow
SpeedThreshold
SleepDelay
PenUpDelay
TouchMode
TouchOptions
CalibrationInset
PenStateReportDelay
TouchReportDelay
Address
Offset
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x11
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3
Value of: 0-255
Value of: 0-255
Value of: 1, 2, 4, 8, 16, 32, 64, 128
Value of: 1, 2, 4, 8, 16, 32, 64, 128
Value of: 1-8
Value of: 1-8
Value of: 0-255
Value of: 0-255
Value of: 0-255
PD2 PD1 PD0 PM1 PM0
–
–
–
–
–
Value of: 0-40
Value of: 0-255
Value of: 0-255
Bit 2
PU2
–
Bit 1
PU1
48W
Bit 0
PU0
CCE
Table 8 : Configuration Registers
Configuration registers are defined as an Offset value from the Start address for the register group.
Default
Value
0xC5
0x04
0x04
0x10
0x02
0x08
0x04
0x64
0x80
0xB1
0x00
0x19
0xC8
0x00
To read or write to a register, do the following.
1) Issue the <Register Start Address Request> command to obtain the Start address for the register group.
2) Calculated the desired register’s absolute address by adding the register’s Offset value to Start address for
the register group.
3) Issue the <Register Read> or <Register Write> command, using the calculated register’s absolute address.
Warning: Use of invalid register value will yield unpredictable results!
7.12.1 TouchThreshold Register (offset 0x02)
The TouchThreshold register sets the threshold for a touch condition to be detected as a touch. A touch is
detected if it is below the TouchThreshold setting. Too small of a value might prevent the controller from
accepting a real touch, while too large of a value might allow the controller to accept very light or false touches
conditions. Valid values are as follows.
0 ≤ TouchThreshold ≤ 255
7.12.2 SensitivityFilter Register (offset 0x03)
The SensitivityFilter register sets the level of touch sensitivity. A higher value is more sensitive to a touch
(accepts a lighter touch), but may exhibit a less stable touch position. A lower value is less sensitive to a touch
(requires a harder touch), but will provide a more stable touch position. Valid values are as follows.
0 ≤ SensitivityFilter ≤ 255
DS41393A-Page 12
© 2009 Microchip Technology, Inc.