M16C28 Datasheet, PDF (57/423 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/28 Group (M16C/28, M16C/28B)
5. Reset
Low Voltage Detection Interrupt Register ⁽¹⁾
b7 b6 b5 b4 b3 b2 b1 b0
Symbol
D4INT
Address
001F16
After Reset
0016
Bit Symbol
D40
D41
Bit Name
Low voltage detection
interrupt enable bit ⁽⁵⁾
STOP mode deactivation
control bit ⁽⁴⁾
Function
RW
0 : Disable
RW
1 : Enable
0: Disable (do not use the low
voltage detection interrupt to exit
stop mode)
1: Enable (use the low voltage
RW
detection interrupt to exit stop
mode)
D42
Voltage change detection flag 0: Not detected
(2)
1: Vdet4 passing detection
RW
(3)
D43
WDT overflow detect flag
0: Not detected
1: Detected
RW
(3)
DF0
Sampling clock select bit
b5b4
00 : CPU clock divided by 8
RW
01 : CPU clock divided by 16
DF1
10 : CPU clock divided by 32
11 : CPU clock divided by 64
RW
(b7-b6)
Nothing is assigned. When write, set to “0”. When read, its
content is “0”.
NOTES:
1. Write to this register after setting the PRC3 bit in the PRCR register to “1” (write enable).
2. Useful when the VC27 bit in the VCR2 register is set to “1” (low voltage detection circuit enabled). If the
VC27 bit is set to “0” (low voltage detection circuit disable), the D42 bit is set to “0” (Not detect).
3. This bit is set to “0” by writing a “0” in a program. (Writing a “1” has no effect.)
4. If the low voltage detection interrupt needs to be used to get out of stop mode again after once used for that
purpose, reset the D41 bit by writing a “0” and then a “1”.
5. The D40 bit is effective when the VC27 bit in the VCR2 register is set to “1”. To set the D40 bit to “1”, follow
the procedure described below.
(1) Set the VC27 bit to “1”.
(2) Wait for td(E-A) until the detection circuit is actuated.
(3) Wait for the sampling time (refer to Table 5.3 Sampling Clock Periods).
(4) Set the D40 bit to “1”.
Figure 5.6 D4INT Register
VCC
RESET
Vdet4
Vdet3r
Vdet3
Vdet3s
VSS
Internal Reset Signal
5.0V
5.0V
VC13 bit in
VCR1 register
VC26 bit in
VCR2 register ⁽¹⁾
VC27 bit in
VCR2 register
Indeterminate
Indeterminate
Indeterminate
Set to “1” by program (reset level detect circuit enable)
Set to “1” by program
(low voltage detection circuit enable)
NOTES :
1. VC26 bit is invalid in stop mode. (the microcomputer is not reset even if input voltage of VCC pin
becomes lower than Vdet3).
Figure 5.7 Typical Operation of Brown-out Detection Reset (Hardware Reset 2)
Rev. 2.00 Jan. 31, 2007 ^{page 37} of 385
REJ09B0047-0200