AK4184 Datasheet, PDF (16/36 Pages) Asahi Kasei Microsystems – TSC with Keypad Scanner and GPIO Expander

[AK4184]
■ System Reset
Upon power-up, all blocks of the AK4184 should be reset by executing RESETN pin = “L”. This ensures that all
internal registers are reset to their initial values (0000H). The touch screen control data is set to X-measurement and
auto driver off (A1 bit=A0 bit = PD bit=“0”). Internal state is fixed and the pen interrupt function is enabled. If the
AVDD and IOVDD are supplied separately, the power up sequence is not critical.
■ Touch Screen Control Command
The control command (4 bits) provided to the AK4184 via DIN is shown in Table 5. This command includes a start bit,
channel selection of ADC input, power-down mode of ADC and the next 12bits (written by “0” data). The AK4184
latches the serial command on the rising edge of SCLK. Detail information regarding the bit order, function, status of
the driver switch, ADC input and reference voltage as shown in Table 6 and Table 7.
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
S
A1 A0 PD
0
0
0000000000
Table 5. Touch Screen Command Word Format
Bits
15
14:13
12
11:0
Name
S
A1-A0
PD
Function
Start Bit. This bit must be “1”
Channel Selection Bits. Analog inputs to the A/D converter and the activated driver
switches are selected. (Table 7)
Power-down Mode (Table 8)
Reserved
Table 6. The definition of touch screen control data
Input
Status of Driver Switch
ADC input Reference Voltage
(ΔAIN)
(ΔVREF)
S A1 A0 XP XN YP YN AIN+ AIN- VREF+ VREF-
Note
1 0 0 ON ON OFF OFF YP XN XP
XN X-axis
1 0 1 OFF OFF ON ON XP YN YP
YN Y-axis
1 1 0 OFF ON ON OFF XP(Z1) XN YP
XN Z1 (Pen Pressure)
1 1 1 OFF ON ON OFF YN(Z2) XN YP
XN Z2 (Pen Pressure)
Table 7. Status of Driver Switch
MS0603-E-00
16
2007/04