10 SUPPLY VOLTAGE DETECTOR (SVD3)
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
10-7
TECHNICAL MANUAL (Rev. 1.0)
Bits 7–4
SVDRE[3:0]
These bits enable/disable the reset issuance function when a low power supply voltage is detected.
0xa (R/WP):
Enable (Issue reset)
Other than 0xa (R/WP): Disable (Generate interrupt)
For more information on the SVD3 reset issuance function, refer to “SVD3 Reset.”
Bit 3
EXSEL
This bit selects the external voltage to be detected when the SVDCTL.VDSEL bit = 1.
1 (R/WP): EXSVD1
0 (R/WP): EXSVD0
Note
: The EXSVD1 pin does not exist depending on the model (see “Power supply voltage to be
detected” in Table
10.1.1)
. In this case, the external voltage detection function does not work
if the
SVDCTL.EXSEL bit is set to 1. When using the
external voltage detection function
(
SVDCTL.VDSEL bit = 1), the SVDCTL.EXSEL bit should be set to 0.
Bits 2–1
SVDMD[1:0]
These bits select intermittent operation mode and its detection cycle.
Table 10.6.4 Intermittent Operation Mode Detection Cycle Selection
SVDCTL.SVDMD[1:0] bits
Operation mode (detection cycle)
0x3
Intermittent operation mode (CLK_SVD3/512)
0x2
Intermittent operation mode (CLK_SVD3/256)
0x1
Intermittent operation mode (CLK_SVD3/128)
0x0
Continuous operation mode
For more information on intermittent and continuous operation modes, refer to “SVD3 Operations.”
Bit 0
MODEN
This bit enables/disables for the SVD3 circuit to operate.
1 (R/WP): Enable (Start detection operations)
0 (R/WP): Disable (Stop detection operations)
After this bit has been altered, wait until the value written is read out from this bit without subsequent
operations being performed.
Notes: • Writing 0 to the SVDCTL.MODEN bit resets the SVD3 hardware. However, the register values
set and the interrupt flag are not cleared. The SVDCTL.MODEN bit is actually set to 0 after
this processing has finished. If 1 is written to the SVDCTL.MODEN bit continuously without
waiting for the bit being read as 0 at this time, writing 0 may be ignored and a malfunction
may occur as the hardware restarts without resetting.
• The SVD3 internal circuit is initialized if the SVDCTL.SVDSC[1:0] bits, SVDCTL.SVDRE[3:0]
bits, or SVDCTL.SVDMD[1:0] bits are altered while SVD3 is in operation after 1 is written to
the SVDCTL.MODEN bit.
SVD3 Status and Interrupt Flag Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
SVDINTF
15–9 –
0x00
–
R
–
8
SVDDT
x
–
R
7–1 –
0x00
–
R
0
SVDIF
0
H1
R/W Cleared by writing 1.
Bits 15–9 Reserved
Bit 8
SVDDT
The power supply voltage detection results can be read out from this bit.
1 (R):
Power supply voltage (V
DD
or EXSVD0/1) < SVD detection voltage V
SVD
or
EXSVD
detection
voltage
V
SVD_EXT
0 (R):
Power supply voltage (V
DD
or EXSVD0/1)
≥
SVD detection voltage V
SVD
or
EXSVD
detection
voltage
V
SVD_EXT