SyncMOS Technologies International, Inc.
SM89T16R1
8-Bits Micro-controller
With 64KB Flash ROM & 1KB RAM & Two UART & RTC & ADC & PWM embedded
PWMD ($B3H and $B4H)
Bit7
Bit6
Bit5
Bit4
Bit3
PWMD.3
Bit2
PWMD.2
Bit1
Bit0
PWMD.7
PWMD.6
PWMD.5
PWMD.4
PWMD.1
PWMD.0
Real Time Clock (RTC)
The on-chip RTC keeps time of second and minute functions. Its time base is a 32.768 KHz crystal between pins
X32OUT (alternate function of ALE) and X32IN (alternate function of PSEN). The RTC maintains time to a second.
It also allows a user to read or write values of seconds and minute.
The RTC function used SFR descriptor as below:
RTCS ($A1H)
Bit7
Bit6
Stable
Bit5
SEC.5
Bit4
SEC.4
Bit3
SEC.3
Bit2
SEC.2
Bit1
SEC.1
Bit0
SEC.0
RTCen
RTCen: When set to ‘1’, enable the enable RTC function. When this bit set, the ALE and PSEN pins output will
disable, and the ALE and PSEN pins will use for RTC function as X32OUT and X32IN.
Stable: Read only. The Stable bit will set to 1 when the RTC module stable. Please wait 2 seconds before used the
RTC function.
SEC [5:0]: show the current second counter at RTC function. The range is from 00H to 3BH.
RTCC ($A2H)
Bit7
Bit6
INT_SEL0
Bit5
MIN.5
Bit4
MIN.4
Bit3
MIN.3
Bit2
MIN.2
Bit1
MIN.1
Bit0
MIN.0
INT_SEL1
INT_SEL [1:0]: the interrupt distribution selection bit, the interrupt vector is 43H.
00: the interrupt is set as 0.5 second
01: the interrupt is set as 1 second
10: the interrupt is set as 30 second
11: the interrupt is set as 60 second
MIN [5:0]: show the current minute counter at RTC function. The range is from 00H to 3BH.
Starting and stopping the RTC:
RTCS ($A1H)
Bit7
Bit6
Stable
Bit5
SEC.5
Bit4
SEC.4
Bit3
SEC.3
Bit2
SEC.2
Bit1
SEC.1
Bit0
SEC.0
RTCen
The RTC Function is enable by set the RTCS.7 (RTCen=1), then the ALE and /PSEN pins will switch to X32OUT
and X32IN that for RTC function used, the ALE and PSEN signal output will disable; the crystal frequency is
32768Hz. See figure 17.
S W 1
R
1
2
J1
32768H z C lock in
1
1
2
R T C en
X32in(/P S E N )
Y 1
32768H z
J2
1
In C hip
X32out(A LE )
Figure 17 The RTC Crystal connect diagram
The stable bit (RTCS.6) will set to 1 when the RTC module stable. The design is about 31.25msec; suggest waiting 2
Specifications subject to change without notice contact your sales representatives for the most recent information.
Ver 2.1 SM89T16R1 08/2006
24
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
