Si4020
6. Low Battery Detector Command
bit
15
1
14
1
13
0
12
0
11
0
10
0
9
1
8
0
7
0
6
0
5
0
4
3
2
1
0
POR
t4
t3
t2
t1
t0
C200h
The 5-bit value T of <t4 : t0> determines the threshold voltage Vlb of the detector:
Vlb = 2.25 V + T * 0.1 V
7. Sleep Command
bit
15
1
14
1
13
0
12
0
11
0
10
1
9
0
8
0
7
6
5
4
3
2
1
0
POR
s7
s6
s5
s4
s3
s2
s1
s0
C400h
The effect of this command depends on the Power Management Command. It immediately disables the power amplifier (if a0=1 and
ea=0) and the synthesizer (if a1=1 and es=0). Stops the crystal oscillator after S periods of the microcontroller clock (if a1=1 and
ex=0) to enable the microcontroller to execute all necessary commands before entering sleep mode itself. The 8-bit value S is
determined by bits <s7 : s0>.
8. Push-Button Command
bit
15
1
14
1
13
0
12
0
11
1
10
0
9
1
8
0
7
6
5
4
3
2
1
0
POR
p4
d1
d0
b4
b3
b2
b1
bc
CA00h
If the corresponding bit was set (b1-b4) the event remains active while the button is pressed. In EEPROM mode, the chip is continuously
performing the routine assigned to the push-button while it is pressed. In microcontroller mode, the chip continuously generates interrupts
on nIRQ until the push-button is released. Weak pull-up currents are switched off when bc is high.
The d0, d1 bits set the de-bouncing time period:
d1
0
d0
0
De-bouncing Time [ms]
160
0
1
40
1
0
10
1
1
0 (Bypassed)
Note:
• Until the de-bouncing time has expired, the crystal oscillator remains switched on, independent of the status of the ex bit in the
Power Management Command. (Because the circuit uses the crystal oscillator signal for timing.)
If the p4 bit is set, the controller performs the routine assigned to the fourth button when PB1 and PB2 are pressed down
simultaneously. With the addition of this feature, there is a way to build a device that uses 3 buttons, but performs 4 functions.
It is possible to detect multiple pressed push-buttons in both modes. In EEPROM mode the controller executes sequentially all the
routines belonging to the pressed buttons.
16
SILICON [ SILICON ]
