aduc831bcp-reel Analog Devices, Inc., aduc831bcp-reel Datasheet - Page 45

• Manufacturer Part Number: aduc831bcp-reel
• Description: Microconverter, 12-bit Adcs And Dacs With Embedded 62 Kbytes Flash Mcu
• Manufacturer: Analog Devices, Inc.

TIME INTERVAL COUNTER (TIC)
A time interval counter is provided on-chip for counting longer
intervals than the standard 8051 compatible timers are capable
of. The TIC is capable of timeout intervals ranging from 1/128
second to 255 hours. Furthermore, this counter is clocked by
an internal R/C oscillator rather than the external crystal and
has the ability to remain active in power-down mode and time
long power-down intervals. This has obvious applications for
remote battery-powered sensors where regular widely spaced
readings are required. The R/C oscillator is accurate to +10% at
25ºC. Note: Instructions to the TIC SFRs are also clocked at
32 kHz, sufficient time must be allowed for in user code for
these instructions to execute.
Six SFRs are associated with the time interval counter, TIMECON
being its control register. Depending on the configuration of the
IT0 and IT1 bits in TIMECON, the selected time counter regis-
ter overflow will clock the interval counter. When this counter is
equal to the time interval value loaded in the INTVAL SFR, the
TII bit (TIMECON.2) is set and generates an interrupt if enabled.
If the ADuC831 is in power-down mode, again with TIC inter-
rupt enabled, the TII bit will wake up the device and resume
code execution by vectoring directly to the TIC interrupt service
vector address at 0053H. The TIC-related SFRs are described
below. Note also that the time-base SFRs can be written initially
with the current time, the TIC can then be controlled and
accessed by user software. In effect, this facilitates the imple-
mentation of a real-time clock. A block diagram of the TIC is
shown in Figure 35.
TIMECON
SFR Address
Power-On Default Value
Bit Addressable
Bit
7
6
5
4
3
2
1
0
REV. 0
Name
----
TFH
ITS1
ITS0
STI
TII
TIEN
TCEN
Description
Reserved for Future Use.
Twenty-Four Hour Select Bit.
Set by the user to enable the Hour counter to count from 0 to 23.
Cleared by the user to enable the Hour counter to count from 0 to 255.
Interval Timebase Selection Bits.
Written by user to determine the interval counter update rate.
ITS1
0
0
1
1
Single Time Interval Bit.
Set by user to generate a single interval timeout. If set, a timeout will clear the TIEN bit.
Cleared by user to allow the interval counter to be automatically reloaded and start counting
again at each interval timeout.
TIC Interrupt Bit.
Set when the 8-bit Interval Counter matches the value in the INTVAL SFR.
Cleared by user software.
Time Interval Enable Bit.
Set by user to enable the 8-bit time interval counter.
Cleared by user to disable the interval counter.
Time Clock Enable Bit.
Set by user to enable the time clock to the time interval counters.
Cleared by user to disable the clock to the time interval counters and reset the time interval SFRs
to the last value written to them by the user. The time registers (HTHSEC, SEC, MIN, and HOUR)
can be written while TCEN is low.
TIC Control Register
No
A1H
00H
Table XVI. TIMECON SFR Bit Designations
ITS0
0
1
0
1
Interval Timebase
1/128 Second
Seconds
Minutes
Hours
–45–
TIME INTERVAL COUNTER INTERRUPT
TCEN
INTERVAL TIMEOUT
32kHz INTERNAL R/C OSC.
Figure 35. TIC, Simplified Block Diagram
HUNDREDTHS COUNTER
SECOND COUNTER
MINUTE COUNTER
HOUR COUNTER
PRESCALER
HOUR
8-BIT
HTHSEC
SEC
MIN
INTERVAL COUNTER
COUNT = INTVAL?
TIME INTERVAL
COMPARE
INTVAL
8-BIT
SELECTION
ADuC831
TIMEBASE
INTERVAL
ITS0, 1
MUX
TIEN