UPD78F0138 NEC, UPD78F0138 Datasheet - Page 382

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

19.1.2 Registers controlling standby function
(1) Oscillation stabilization time counter status register (OSTC)
382
The standby function is controlled by the following two registers.
• Oscillation stabilization time counter status register (OSTC)
• Oscillation stabilization time select register (OSTS)
Remark For the registers that start, stop, or select the clock, see CHAPTER 5 CLOCK GENERATOR.
This is the status register of the X1 input clock oscillation stabilization time counter. If the Ring-OSC clock is used
as the CPU clock, the X1 input clock oscillation stabilization time can be checked.
OSTC can be read by a 1-bit or 8-bit memory manipulation instruction.
Reset release (reset by RESET input, POC, LVI, clock monitor, and WDT), the STOP instruction, MSTOP (bit 7 of
MOC register) = 1, and MCC (bit 7 of PCC register) = 1 clear OSTC to 00H.
Address: FFA3H
Symbol
OSTC
Figure 19-1. Format of Oscillation Stabilization Time Counter Status Register (OSTC)
Cautions 1. After the above time has elapsed, the bits are set to 1 in order from MOST11 and
Remarks 1. Values in parentheses are reference value for operation with f
MOST11
7
0
1
1
1
1
1
After reset: 00H
2. f
2. If the STOP mode is entered and then released while the Ring-OSC clock is
3. The wait time when STOP mode is released does not include the time after
MOST13
X
remain 1.
being used as the CPU clock, set the oscillation stabilization time as follows.
The X1 oscillation stabilization time counter counts only during the oscillation
stabilization time set by OSTS. Therefore, note that only the statuses during the
oscillation stabilization time set by OSTS are set to OSTC after STOP mode has
been released.
STOP mode release until clock oscillation starts (“a” below) regardless of
whether STOP mode is released by RESET input or interrupt generation.
: X1 input clock oscillation frequency
• Desired OSTC oscillation stabilization time ≤ Oscillation stabilization time
6
0
0
1
1
1
1
set by OSTS
X1 pin voltage
waveform
R
CHAPTER 19 STANDBY FUNCTION
MOST14
User’s Manual U16228EJ2V0UD
5
0
0
0
1
1
1
STOP mode release
MOST11
MOST15
4
0
0
0
1
1
a
MOST13
MOST16
3
0
0
0
0
1
2
2
2
2
2
MOST14
11
13
14
15
16
Oscillation stabilization time status
/f
/f
/f
/f
/f
X
X
X
X
X
2
min. (204.8
min. (819.2
min. (1.64 ms min.)
min. (3.27 ms min.)
min. (6.55 ms min.)
MOST15
X
µ
µ
= 10 MHz.
1
s min.)
s min.)
MOST16
0