R8C2A Datasheet, PDF (70/609 Pages) Renesas Technology Corp – MCU

R8C/2A Group, R8C/2B Group
6. Voltage Detection Circuit
6.2 Voltage Monitor 0 Reset
Table 6.2 lists the Procedure for Setting Bits Associated with Voltage Monitor Reset and Figure 6.9 shows an
Example of Voltage Monitor 0 Reset Operation. To use the voltage monitor 0 reset to exit stop mode, set the
VW0C1 bit in the VW0C register to 1 (digital filter disabled).
Table 6.2 Procedure for Setting Bits Associated with Voltage Monitor Reset
Step
1
2
3
4⁽¹⁾
5⁽¹⁾
6
7
8
9
When Using Digital Filter
When Not Using Digital Filter
Set the VCA25 bit in the VCA2 register to 1 (voltage detection 0 circuit enabled)
Wait for td(E-A)
Select the sampling clock of the digital filter Set the VW0C7 bit in the VW0C register to
by the VW0F0 to VW0F1 bits in the VW0C 1
register
Set the VW0C1 bit in the VW0C register to Set the VW0C1 bit in the VW0C register to
0 (digital filter enabled)
1 (digital filter disabled)
Set the VW0C6 bit in the VW0C register to 1 (voltage monitor 0 reset mode)
Set the VW0C2 bit in the VW0C register to 0
Set the CM14 bit in the CM1 register to 0 −
(low-speed on-chip oscillator on)
Wait for 4 cycles of the sampling clock of − (No wait time required)
the digital filter
Set the VW0C0 bit in the VW0C register to 1 (voltage monitor 0 reset enabled)
NOTE:
1. When the VW0C0 bit is set to 0, steps 3, 4, and 5 can be executed simultaneously (with 1
instruction).
Vdet0
VCC
When the VW0C1 bit is set
to 0 (digital filter enabled)
Internal reset signal
Sampling clock of
digital filter × 4 cycles
When the VW0C1 bit is set
to 1 (digital filter disabled)
and the VW0C7 bit is set
to 1
Internal reset signal
1
fOCO-S
×
32
1
fOCO-S
×
32
VW0C1 and VW0C7: Bits in VW0C register
The above applies under the following conditions.
• VCA25 bit in VCA2 register = 1 (voltage detection 0 circuit enabled)
• VW0C0 bit in VW0C register = 1 (voltage monitor 0 reset enabled)
• VW0C6 bit in VW0C register = 1 (voltage monitor 0 reset mode)
When the internal reset signal is held “L”, the pins, CPU and SFR are reset.
The internal reset signal level changes from “L” to “H”, and a program is executed beginning with the address indicated by
the reset vector.
Refer to 4. Special Function Registers (SFRs) for the SFR status after reset.
Figure 6.9 Example of Voltage Monitor 0 Reset Operation
Rev.2.00 Nov 26, 2007 Page 50 of 580
REJ09B0324-0200