Cr Oscillation Frequency Monitoring Function; Interrupts - Epson Arm S1C31 Series Technical Manual

External part tolerances
Power supply voltage fluctuations
Parasitic capacitance and resistance of the board
Temperature
Unevenness of IC quality

21.4.5 CR Oscillation Frequency Monitoring Function

The CR oscillation clock (RFCLK) generated during converting operation can be output from the RFCLKOn pin
for monitoring. By setting the RFC_nCTL.CONEN bit to 1, the RFC Ch.n enters continuous oscillation mode that
disables oscillation stop conditions to continue oscillating operations. In this case, set the the RFC_nTRG.SREF bit
(reference oscillation), the RFC_nTRG.SSENA bit (sensor A oscillation), or the RFC_nTRG.SSENB bit (sensor B
oscillation) to 1 to start oscillation. Set the bit to 0 to stop oscillation. Using this function helps easily measure the
CR oscillation clock frequency. Furthermore, setting the RFC_nCTL.RFCLKMD bit to 1 changes the output clock
to the divided-by-two RFCLK clock.
RFC_nCTL.CONEN
RFC_nTRG.SSENA, SSENB, SREF
(RFC_nCTL.RFCLKMD = 0)
(RFC_nCTL.RFCLKMD = 1)

21.5 Interrupts

The RFC has a function to generate the interrupts shown in Table 21.5.1.
Interrupt
Reference oscillation RFC_nINTF.EREFIF
completion
Sensor A oscillation RFC_nINTF.ESENAIF When sensor A oscillation has been completed normally
completion
Sensor B oscillation RFC_nINTF.ESENBIF When sensor B oscillation has been completed normally
completion
Measurement counter RFC_nINTF.OVMCIF When sensor oscillation has been terminated abnormally
overflow error
Time base counter RFC_nINTF.OVTCIF
overflow error
The RFC provides interrupt enable bits corresponding to each interrupt flag. An interrupt request is sent to the CPU
only when the interrupt flag, of which interrupt has been enabled by the interrupt enable bit, is set. For more infor-
mation on interrupt control, refer to the "Interrupt" chapter.
S1C31D41 TECHNICAL MANUAL
(Rev. 1.1)
Table 21.4.4.1 Error Factors
Error factor
RFINn pin
RFCLKOn pin
RFCLKOn pin
Figure 21.4.5.1 CR Oscillation Clock (RFCLK) Waveform
Table 21.5.1 RFC Interrupt Function
Interrupt flag
When reference oscillation has been completed normally
due to a measurement counter overflow
due to the time base counter reaching 0x000000
due to the time base counter reaching 0x000000
due to a measurement counter overflow
When reference oscillation has been terminated abnor-
mally due to a time base counter overflow
Seiko Epson Corporation
Influence
Large
Large
Middle
Small
Small
Writing 1
Set condition
21 R/F CONVERTER (RFC)
Writing 0
V
DD
V
SS
V
DD
V
SS
Clear
condition
Writing 1
Writing 1
Writing 1
Writing 1
Writing 1
21-7