Renesas PROM Programming Adapters PCA7438F-64A Specifiche Pagina 39
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Rev.2.40 Jun 14, 2004 page 39 of 56
38C1 Group
CLOCK GENERATING CIRCUIT
The oscillation circuit of 38C1 group can be formed by connecting
an oscillator, capacitor and resistor between XIN and XOUT (XCIN
and XCOUT). To supply a clock signal externally, input it to the XIN
pin and make the XOUT pin open. The clocks that are externally
generated cannot be directly input to X
CIN. Use the circuit con-
stants in accordance with the oscillator manufacturer's recom-
mended values. No external resistor is needed between X
IN and
XOUT since a feed-back resistor exists on-chip. However, a 10 MΩ
external feed-back resistor is needed between XCIN and XCOUT.
Immediately after reset is released, only the on-chip oscillator
starts oscillating, XIN -XOUT oscillation stops oscillating, and XCIN
and XCOUT pins function as I/O ports.
Operation mode
(1) On-chip oscillator mode
The internal clock φ is the on-chip oscillator oscillation divided by
8.
(2) Middle-speed mode
The internal clock φ is the frequency of XIN divided by 8.
(3) High-speed mode
The internal clock φ is half the frequency of XIN.
(4) Low-speed mode
The internal clock φ is half the frequency of XCIN.
After reset release and when system returns from the stop mode,
the on-chip oscillator mode is selected.
Refer to the clock state transition diagram for the setting of transi-
tion to each mode.
The XIN–XOUT oscillation is controlled by the bit 5 of CPUM, and
the sub-clock oscillation is controlled by the bit 4 of CPUM. When
the mode is switched to the on-chip oscillator mode, set the bit 3
of CPUM to “1”.
In the on-chip oscillator mode, the oscillation by the oscillator can
be stopped. In the low-speed mode, the power consumption can
be reduced by stopping the XIN–XOUT oscillation.
When the mode is switched from the on-chip oscillator mode to
the low-speed mode, the on-chip oscillator is stopped.
Set enough time for oscillation to stabilize by programming to re-
start the stopped oscillation and switch the operation mode. Also,
set enough time for oscillation to stabilize by programming to
switch the timer count source .
Note: If you switch the mode between on-chip oscillator mode,
middle/high-speed mode and low-speed mode, stabilize
both XIN and XCIN oscillations. Especially be careful imme-
diately after power-on and at returning from stop mode. Re-
fer to the clock state transition diagram for the setting of
transition to each mode. Set the frequency in the condition
that f(XIN) > 3•f(XCIN).
When the middle- and high-speed mode are not used (XIN-
XOUT oscillation and external clock input are not
performed), connect XIN to VCC through a resistor.
Fig. 40 Oscillator circuit example
Fig. 41 External clock input circuit
Oscillation Control
(1) Stop mode
Set the timer 1 interrupt enable bit to disabled (“0”) before execut-
ing the STP instruction. If the STP instruction is executed, the in-
ternal clock φ stops at an “H” level, and main clock, on-chip oscil-
lator and sub-clock oscillators stop.
In this time, “10
16” is set to timer 1 and the on-chip oscillator is
connected forcibly for the system clock and the timer 1 count
source. Also, the bits of the timer 123 mode register except bit 4
are cleared to “0”.
When an external interrupt is received, the clock oscillated before
stop mode and the on-chip oscillator start oscillating.
However, bit 3 of CPUM is set to “1” forcibly and system returns to
the on-chip oscillator mode.
Tthe internal clock φ is supplied to the CPU after timer 1
underflows. However, when the system clock is switched from the
on-chip oscillator to main clock and sub-clock, generate the wait
time enough for oscillation stabilizing by program.
(2) Wait mode
If the WIT instruction is executed, only the internal clock φ stops at
an “H” level. The states of main clock, on-chip oscillator and sub-
clock are the same as the state before the executing the WIT in-
struction and the oscillation does not stop. Since the internal clock
φ restarts when an interrupt is received, the instruction is executed
immediately.
X
CIN
C
IN
C
OUT
C
CIN
C
COUT
Rf
Rd
X
OUT
X
IN
X
COUT
External oscillation circuit
O
p
e
n
V
C
C
V
S
S
C
C
I
N
R
f
R
d
C
C
O
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T
X
C
I
N
X
OUT
X
I
N
X
C
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T
- 38C1 Group 1
- PIN CONFIGURATION (TOP VIEW) 2
- FUNCTIONAL BLOCK DIAGRAM 3
- PIN DESCRIPTION 4
- PART NUMBERING 5
- GROUP EXPANSION 6
- Memory Type 6
- Memory Size 6
- Packages 6
- I/O PORTS 13
- Pull-up/Pull-down Control 13
- INTERRUPTS 18
- Interrupt Control 18
- Interrupt Operation 18
- Timer 1, Timer 2, Timer 3 24
- ■Note on Timer 1 to Timer 3 24
- Serial I/O 25
- ADKEY Control Circuit 28
- LCD DRIVE CONTROL CIRCUIT 30
- Power Input Pins 32
- LCD Display register 33
- LCD Drive Timing 33
- OTHER FUNCTION REGISTERS 36
- RESET CIRCUIT 37
- N.G. O.K 43
- ROM PROGRAMMING METHOD 45
- DATA REQUIRED FOR MASK ORDERS 45
- ELECTRICAL CHARACTERISTICS 46
- Absolute Maximum Ratings 46
- CIN) < f(XIN)/3 49
- IN), the rating 49
- Electrical Characteristics 50
- IN) ≥ 500 kHz 52
- OUT, XCOUT pins are excluded 54
- PACKAGE OUTLINE 56
- 3 = 1 → CM3 = * (Note 9) 57
- RENESAS SALES OFFICES 59
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