
172
EPSON
S1C88409 TECHNICAL MANUAL
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (Touch Panel Controller)
PRTP: Touch panel controller clock control
register (00FF16HD3)
Controls the clock supply of the touch panel
controller.
When "1" is written: ON
When "0" is written: OFF
Reading: Valid
By writing "1" to the PRTP register, the clock that is
selected with the PSTP register is output to the
touch panel controller.
When "0" is written, the clock is not output.
At initial reset, the PRTP register is set to "0" (OFF).
VRC: AVREF control register (00FF80HD4)
Enables the AVREF control function.
When "1" is written: Enabled
When "0" is written: Disabled
Reading: Valid
Writing "1" to the VRC register enables the AVREF
control function.
An I/O port (P30–P37) which is not used for
inputting analog signals can be used to switch the
external AVREF input. Set the I/O port in the
output mode and write "1" to the data register.
When the touch panel controller needs A/D
conversion, it turns the I/O port terminal to low.
The signal drives the external transistor to supply
AVREF to the A/D converter.
PDC: Pen-down check control register
(00FFA0HD6)
Controls the pen-down check operation.
When "1" is written: Check
When "0" is written: Cancel
Reading: Valid
When "1" is written to the PDC register, the pen-
down check starts. The pen-down check generates
an interrupt when a pen-down is detected. Start
coordinate detection using the interrupt. It is
necessary to enable the pen-down interrupt before
starting pen-down check.
When "0" is written to the PDC register, the pen-
down check stops.
The pen-down function is effective only when the
touch panel controller is in reset status (RST="0").
At initial reset, the PDC register is set to "0"
(cancel).
RST: TPC circuit reset control register
(00FFA0HD5)
Controls coordinate detection.
When "1" is written: Cancel
When "0" is written: Reset
Reading: Valid
When "1" is written to the RST register, the touch
panel controller circuit starts coordinate detection.
When "0" is written, the circuit stops coordinate
detection and goes into reset status.
Set the touch panel controller circuit to reset status
to reduce current consumption when the touch
panel operation is not necessary.
At initial reset, the RST register is set to "0" (reset).
CONST: Mode setting register (00FFA0HD4)
Sets the operating mode of the touch panel
controller.
When "1" is written: Constant-speed mode
When "0" is written: Normal mode
Reading: Valid
When "1" is written to the CONST register, the touch
panel controller is set in the constant-speed mode.
When "0" is written. It is set in the normal mode.
The constant-speed mode does not judge drawing
speed and gets coordinate values by constant
arithmetic mean set with the AVN register. The
coordinate detection speed is always constant in
this mode.
In the normal mode, the hardware changes the
number of A/D conversions for arithmetic mean
in five stages according to the drawing speed.
At initial reset, the CONST register is set to "0"
(normal mode).
AVN0–AVN2: Mean count setting register for
constant-speed mode (00FFA0HD0–D2)
Sets the arithmetic mean count (number of A/D
conversion) for constant-speed mode.
Table 5.17.6.2 Mean count for constant-speed mode
AVN2
0
1
AVN1
0
1
×
AVN0
0
1
0
1
×
Number of
A/D conversion
16
×16
16
×8
16
×4
16
×2
16
×1
The setting in this register is invalid in the normal
mode.
The set number of A/D conversions are performed
for both the X and Y coordinates.
At initial reset, the AVN register is set to "0" (256
times).