M16C26 Datasheet, PDF (21/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

Udenvdeelropment
Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative and subject to change.
Reset
M16C/26 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Voltage detection circuit
The voltage detection circuit has monitoring circuits to check the input voltage of the VCC pin. These
circuits monitor the the input voltage at VDET3 and VDET4. Bits VC26 and VC27 of VCR2 register are
used to enable/disable these monitoring circuits.
The VDET3 monitoring circuit is used for detecting the minimum VCC that guarantees proper chip
operation.
The VDET4 monitoring circuit can be set to detect whether the input voltage is equal to and greater or
less than VDET4 depending on the value of VC13 bit of the VCR1 register. In addition, the VDET4
monitoring circuit, if enabled, can generate an interrupt.
RESET
VCR2 register
b7 b6
Write to WDC register
Internal power on reset
CM10 bit = 1
(stop mode)
+
> VDET3
E
WDC5 bit
S
Q
R
WARM/COLD
(warm or cold start)
1 shot
CK
Internal power
supply voltage
stable time
td(S-R)
Q
Internal reset
("L" active)
VCC
Figure 1.5.4. Reset circuit block
+
≥ VDET4
E
Noise rejection
VDET4 detect signal
VCR1 register
b3
VC13 bit
Watchdog timer control register
b7 b6 b5 b4 b3 b2 b1 b0
0
Symbol
WDC
Address After reset
000F16 00?XXXXX2(Note1)
Bit symbol
Bit name
Function
RW
High-order bit of watchdog timer
RO
WDC5
Cold start / warm start 0 : Cold start
discrimination flag (Note 2) 1 : Warm start
RW
Reserved bit
Set to 0
RW
WDC7 Prescaler select bit
0 : Divided by 16
1 : Divided by 128
RW
Note 1: The WDC5 bit is set to 0 immediately after power-on (cold start).
Note 2: The WDC5 bit will always be set to a 1 whenever the WDC SFR is written (regardless of value of WDC5 bit).
Figure 1.5.5. WDC register
15
Renesas Technology Corp.