23 SUPPLY VOLTAGE DETECTOR (SVD)
23-4
EPSON
S1C17704 TECHNICAL MANUAL
23.4 SVD Interrupt
The SVD module can generate an interrupt when supply voltage drop has been detected.
Supply voltage drop detection interrupt
This interrupt request occurs when the SVD module being operated (SVDEN (D0/SVD_EN register) = 1)
detects that the supply voltage (V
DD
) drops under the compare voltage, and it sets the interrupt flag SVDIF (D0/
SVD_IFLG register) in the SVD module to 1. Note that the SVDIF, which has been set to 1, cannot be reset
even if the supply voltage returns over the compare voltage after that.
∗
SVDIF
: SVD Interrupt Flag in the SVD Interrupt Flag (SVD_IFLG) Register (D0/0x5104)
Set the SVDIE bit (D0/SVD_IMSK register) to 1 when using this interrupt. If SVDIE is set to 0 (default), an
interrupt request by this cause will not be sent to the interrupt controller (ITC).
∗
SVDIE
: SVD Interrupt Enable Bit in the SVD Interrupt Mask (SVD_IMSK) Register (D0/0x5103)
If SVDIF is set to 1 when the SVDIE has been set to 1 (interrupt enabled), the SVD module outputs the
interrupt request signal to the ITC. The interrupt request signal sets the SVD interrupt flag in the ITC to 1 and
an interrupt occurs if other interrupt conditions meet the ITC and S1C17 Core settings.
The interrupt handler routine must reset (write 1 to) SVDIF in the SVD module, not the SVD interrupt flag in
the ITC, to clear the cause of interrupt.
Notes
: • No interrupt will occur if the supply voltage is already lower than the compare voltage at the
time SVDIE is set to 1 (interrupt enabled).
• To avoid occurrence of unnecessary interrupts, be sure to reset the SVDIF flag before the
SVD interrupt is enabled using SVDIE.
ITC registers for SVD interrupt
When the SVD module has detected supply voltage drop, the SVD asserts the interrupt signal sent to the ITC
according to the interrupt condition settings shown above. To generate an SVD interrupt, set the interrupt level
and enable the interrupt using the ITC registers.
The following shows the control bits for the SVD interrupt in the ITC.
Interrupt flag in the ITC
∗
EIFT5
: SVD Interrupt Flag in the Interrupt Flag (ITC_IFLG) Register (D5/0x4300)
Interrupt enable bit in the ITC
∗
EIEN5
: SVD Interrupt Enable Bit in the Interrupt Enable (ITC_EN) Register (D5/0x4302)
Interrupt level setup bits in the ITC
∗
EILV5[2:0]
: SVD Interrupt Level Bits in the External Interrupt Level Setup (ITC_ELV2) Register 2 (D[10:8]/0x430a)
Interrupt trigger mode select bit in the ITC (fixed at 1)
∗
EITG5
: SVD Interrupt Trigger Mode Select Bit in the External Interrupt Level Setup (ITC_ELV2) Register 2
(D12/0x430a)
When the SVD module has detected supply voltage drop, EIFT5 is set to 1.
If EIEN5 has been set to 1, the ITC sends an interrupt request to the S1C17 Core. To disable the SVD interrupt,
set EIEN5 to 0. EIFT5 is always set to 1 by the interrupt signal sent from the SVD module, regardless of how
EIEN5 is set (even when set to 0).
EILV5[2:0] sets the interrupt level (0 to 7) of the SVD interrupt.
An interrupt request to the S1C17 Core is accepted only when all the conditions described below are met.
• The interrupt enable bit is set to 1.
• The IE (Interrupt Enable) bit of the PSR (Processor Status Register) in the S1C17 Core is set to 1.
• The SVD interrupt has a higher interrupt level than the value that is set in the IL field of the PSR.
• No other cause of interrupt having higher priority, such as NMI, has occurred.
For details on these interrupt control registers, as well as the device operation when an interrupt has occurred,
see Chapter 6, “Interrupt Controller (ITC).”
Summary of Contents for S1C17704
Page 1: ...TECHNICAL MANUAL S1C17704 CMOS 16 BIT SINGLE CHIP MICROCOMPUTER ...
Page 22: ...1 OVERVIEW 1 10 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 42: ...3 MEMORY MAP BUS CONTROL 3 12 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 82: ...6 INTERRUPT CONTROLLER ITC 6 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 108: ...8 CLOCK GENERATOR CLG 8 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 112: ...9 PRESCALER PSC 9 4 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 138: ...10 I O PORTS P 10 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 156: ...11 16 BIT TIMERS T16 11 18 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 208: ...14 8 BIT OSC1 TIMER T8OSC1 14 16 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 234: ...16 STOPWATCH TIMER SWT 16 14 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 242: ...17 WATCHDOG TIMER WDT 17 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 264: ...18 UART 18 22 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 300: ...20 I2C 20 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 320: ...21 REMOTE CONTROLLER REMC 21 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 360: ...24 ON CHIP DEBUGGER DBG 24 6 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
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