ENA1425 Datasheet, PDF (18/35 Pages) ON Semiconductor – Duty LCD Display Driver with Key Input Function

LC75806PT
Output Data
1. KD1 to KD30 … Key data
When a key matrix of up to 30 keys is formed from the KS1 to KS6 output pins and KI1 to KI5 input pins and one of
those keys is pressed, the key output data corresponding to that key will be set to 1. The table shows the relationship
between those pins and the key data bits.
KI1
KI2
KI3
KI4
KI5
KS1/S75
KD1
KD2
KD3
KD4
KD5
KS2/S76
KD6
KD7
KD8
KD9
KD10
KS3
KD11
KD12
KD13
KD14
KD15
KS4
KD16
KD17
KD18
KD19
KD20
KS5
KD21
KD22
KD23
KD24
KD25
KS6
KD26
KD27
KD28
KD29
KD30
When the KS1/S75 and KS2/S76 output pins are selected to be segment outputs by control data bits K0 and K1 and a
key matrix of up to 20 keys is formed using the KS3 to KS6 output pins and the KI1 to KI5 input pins, the KD1 to
KD10 key data bits will be set to 0.
2. SA … Sleep acknowledge data
This output data bit is set to the state when the key was pressed. Also, while DO will be low in this case, if serial data
is input and the mode is set (to normal or sleep mode) during this period, that mode will be set. SA will be 1 in sleep
mode and 0 in normal mode.
Sleep Mode Functions
Sleep mode is set up by setting S0 or S1 in the control data to 1. When sleep mode is set up, both the segment and
common outputs will go to the low level. In RC oscillator operating mode (OC=0), the oscillator on the OSC pin will
stop (although it will operate during key scan operations), and in exeternal clock operating mode (OC=1), acceptance of
the external clock signal on the OSC pin will stop (although the clock signal will be accepted during key scan
operations). Thus this mode reduces power consumption. However, the S1/P1 to S8/P8, P9/S77 output pins can be used
as general-purpose output ports under control of the P0 to P3, PC90 and PC91 bits in the control data even in sleep
mode (The P9/S77 output pin can not be used as clock output port). Sleep mode is cancelled by setting both S0 and S1
in control data to 0.
Key Scan Operation Functions
1. Key scan timing
The key scan period is 288T[s]. To reliably determine the on/off state of the keys, the LC75806PT scans the keys
twice and determines that a key has been pressed when the key data agrees. It outputs a key data read request (a low
level on DO) 615T[s] after starting a key scan. If the key data does not agree and a key was pressed at that point, it
scans the keys again. Thus the LC75806PT cannot detect a key press shorter than 615T[s].
KS1
*4
1
1
*4
KS2
*4
2
2
*4
KS3
*4
3
3
*4
KS4
*4
4
4
*4
KS5
*4
5
5
*4
KS6
6
6
Key on
576T[s]
Note: *4. These are set to the high or low level by the S0 and S1 bits in the control data.
Key scan output signals are not output from pins that are set to the low level.
1
1
T= _fOSC = _fCK
No.A1425-18/35