sh66l16a SinoWealth Micro-Electronics Corp. Ltd, sh66l16a Datasheet - Page 14

• Manufacturer Part Number: sh66l16a
• Description: 16k 4-bit Low Power Micro-controller With Lcd Driver
• Manufacturer: SinoWealth Micro-Electronics Corp. Ltd

8. Base Timer
The Base timer generates the different frequency interrupt for real time clock based on the value of BTM. The heavy load
register, HVL, is used to switch 32.768kHz Crystal oscillator into heavy load mode that makes the oscillation easier in the
startup period but more current is needed.
After the Base timer is enabled, it counts every clock-input signal. When it counts to $FF, right after next clock input, counter
counts to $00 and generates an overflow. This causes the interrupt of the Base timer interrupt request flag to 1. Therefore, the
Base timer can function as an interval timer periodically; generating overflow output as every 256th clock signal output.
Base Timer Mode Registers (BTM):
To achieve the above interrupt periods, system register $06 and $07 (BTL and BTH) must be cleared to 0 for both.
Programming Notes:
1. If the “ System Clock selection” code option is equal to CK = 0,0 (200kHz RC as system clock with 32.768kHz Crystal for the
2. If the “ System Clock selection” code option is equal to CK = 1,0 (32.768kHz Crystal as system clock), the Base Timer clock
3. If the “ System Clock selection” code option is equal to CK = 1,1 (200kHz RC as system clock), the Base Timer clock source
Address
BTM.2
Base Timer), or CK = 0,1 (200kHz RC as system clock with 32kHz RC for the Base Timer), the Base Timer clock source is
fetched from the OSC (32.768kHz Crystal or 32kHz RC) oscillator. The initial value of the BTM register is 00H.It means that
the Base Timer can be controlled ON/OFF by the BTM register’s software writing. Meanwhile, the OSC (32.768kHz Crystal or
32kHz RC) oscillator can also be turned ON/OFF by this value. Thus, the Base Timer can operate even in the STOP mode if
the BTM register’s value is non-zero. In this case, the clock source of the Alarm carrier and the LCD driver will be selected
from the OSC (32.768kHz Crystal or 32kHz RC) oscillator.
source will be fetched from the OSC (32.768kHz Crystal) oscillator if it is used. The Base Timer can be controlled ON/OFF by
the BTM register’s software writing. If the BTM register is cleared to 00H in system operation, the device will not stop the
32.768KHz Crystal oscillator, but stop Base Timer operating only. In this case, the clock source of the Alarm carrier and the
LCD driver will be selected from the system clock (32.768kHz Crystal OSC).
will be fetched from the OSCX (200kHz RC) oscillator if it is used. The Base Timer can be controlled ON/OFF by the BTM
register’s software writing. If the BTM register is cleared to 00H in system operation, the device will not stop the OSCX
200kHz RC oscillator, but stop Base Timer operating only. In this case, the clock source of the Alarm carrier and the LCD
driver will be selected from the system clock (200kHz RC OSCX).
$03
0
0
0
0
1
1
1
1
BTM .1
Bit3
HVL
0
0
1
1
0
0
1
1
BTM.0
BTM.2
Bit2
0
1
0
1
0
1
0
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
BTM.1
Bit1
Stop (Power on initial)
BTM.0
Interrupt Period
Bit0
0.5Hz
16Hz
32Hz
1Hz
2Hz
4Hz
8Hz
R/W
R/W
14
Base timer mode register (BTM)
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
32kHz RC or 32.768kHz Crystal or 200kHz RC
Remarks
Clock Source
SH66L16A