cop888kg National Semiconductor Corporation, cop888kg Datasheet - Page 18

• Manufacturer Part Number: cop888kg
• Description: 8-bit Cmos Rom Based Microcontrollers With 4k To 24k Memory, Comparators And Usart
• Manufacturer: National Semiconductor Corporation

www.national.com
Reset
RC
Oscillator Circuits
The chip can be driven by a clock input on the CKI input pin
which can be between DC and 10 MHz. The CKO output
clock is on pin G7 (crystal configuration). The CKI input fre-
quency is divided down by 10 to produce the instruction
cycle clock (1/t
Figure 7 shows the Crystal and R/C oscillator diagrams.
CRYSTAL OSCILLATOR
CKI and CKO can be connected to make a closed loop crys-
tal (or resonator) controlled oscillator.
Table 1 shows the component values required for various
standard crystal values.
R/C OSCILLATOR
By selecting CKI as a single pin oscillator input, a single pin
R/C oscillator circuit can be connected to it. CKO is available
as a general purpose input, and/or HALT restart input.
Table 2 shows the variation in the oscillator frequencies as
functions of the component (R and C) values.
(k )
TABLE 1. Crystal Oscillator Configuration, T
R1
0
>
FIGURE 7. Crystal and R/C Oscillator Diagrams
5 x Power Supply Rise Time
FIGURE 6. Recommended Reset Circuit
(M )
R2
1
(Continued)
c
).
(pF)
C1
30
30–36
(pF)
C2
DS012829-9
DS012829-8
CKI Freq
(MHz)
10
DS012829-7
Conditions
V
A
CC
= 25˚C
= 5V
18
Note: 3k
CONTROL REGISTERS
CNTRL Register (Address X'00EE)
The Timer1 (T1) and MICROWIRE/PLUS control register
contains the following bits:
PSW Register (Address X'00EF)
The PSW register contains the following select bits:
The Half-Carry flag is also affected by all the instructions that
affect the Carry flag. The SC (Set Carry) and R/C (Reset
Carry) instructions will respectively set or clear both the carry
flags. In addition to the SC and R/C instructions, ADC,
SUBC, RRC and RLC instructions affect the Carry and Half
Carry flags.
T1C3
Bit 7
Bit 7
(k )
(k )
HC
3.3
5.6
6.8
R1
T1C3
T1C2
T1C1
T1C0
MSEL
IEDG
SL1 & SL0
HC
C
T1PNDA Timer T1 Interrupt Pending Flag (Autoreload
T1ENA
EXPND
BUSY
EXEN
GIE
R
0
0
TABLE 2. RC Oscillator Configuration, T
50 pF
C
T1C2
(M )
(pF)
100
100
R
82
R2
C
1
1
T1PNDA
C
200k
Half Carry Flag
Carry Flag
RA in mode 1, T1 Underflow in Mode 2, T1A
capture edge in mode 3)
Timer T1 Interrupt Enable for Timer Underflow
or T1A Input capture edge
External interrupt pending
MICROWIRE/PLUS busy shifting flag
Enable external interrupt
Global interrupt enable (enables interrupts)
200 pF
T1C1
Timer T1 mode control bit
Timer T1 mode control bit
Timer T1 mode control bit
Timer T1 Start/Stop control in timer
modes 1 and 2, T1 Underflow Interrupt
Pending Flag in timer mode 3
Selects G5 and G4 as MICROWIRE/PLUS
signals SK and SO respectively
External interrupt edge polarity select
(0 = Rising edge, 1 = Falling edge)
Select the MICROWIRE/PLUS clock divide
by (00 = 2, 01 = 4, 1x = 8)
(pF)
200
CKI Freq
2.2 to 2.7
1.1 to 1.3
0.9 to 1.1
C1
30
(MHz)
T1ENA
100–150
T1C0
30–36
(pF)
C2
EXPND
MSEL
Instr. Cycle
8.8 to 10.8
3.7 to 4.6
7.4 to 9.0
CKI Freq
(µs)
(MHz)
0.455
IEDG
4
BUSY
Conditions
SL1
V
Conditions
A
EXEN
V
V
V
V
CC
= 25˚C
CC
CC
CC
CC
= 2.5V
= 5V
= 5V
= 5V
= 5V
SL0
Bit 0
Bit 0
GIE