19 R/F CONVERTER (RFC)
S1C17F13 TeChniCal Manual
Seiko epson Corporation
19-7
(Rev. 1.0)
4.4.1 Error Factors
Table 19.
Error factor
Influence
External part tolerances
Large
Power supply voltage fluctuations
Large
Parasitic capacitance and resistance of the board
Middle
Temperature
Small
Unevenness of IC quality
Small
CR Oscillation Frequency Monitoring Function
19.4.5
The CR oscillation clock (RFCLK) generated during converting operation can be output from the RFCLKO
n
pin
for monitoring. By setting the RFC
n
CTL.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
n
TRG.SREF bit
(reference oscillation), the RFC
n
TRG.SSENA bit (sensor A oscillation), or the RFC
n
TRG.SSENB bit (sensor B os-
cillation) 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
n
CTL.RFCLKMD bit to 1 changes the output clock to the
divided-by-two RFCLK clock.
RFIN
n
pin
RFCLKO
n
pin
(RFC
n
CTL.RFCLKMD = 0)
RFCLKO
n
pin
(RFC
n
CTL.RFCLKMD = 1)
RFC
n
TRG.SSENA, SSENB, SREF
V
DD
V
SS
V
DD
V
SS
RFC
n
CTL.CONEN
Writing 1
Writing 0
4.5.1 CR Oscillation Clock (RFCLK) Waveform
Figure 19.
Interrupts
19.5
The RFC has a function to generate the interrupts shown in Table 19.5.1.
5.1 RFC Interrupt Function
Table 19.
Interrupt
Interrupt flag
Set condition
Clear
condition
Reference oscillation
completion
RFC
n
INTF.EREFIF
When reference oscillation has been completed normally
due to a measurement counter overflow
Writing 1
Sensor A oscillation
completion
RFC
n
INTF.ESENAIF When sensor A oscillation has been completed normally
due to the time base counter reaching 0x000000
Writing 1
Sensor B oscillation
completion
RFC
n
INTF.ESENBIF When sensor B oscillation has been completed normally
due to the time base counter reaching 0x000000
Writing 1
Measurement counter
overflow error
RFC
n
INTF.OVMCIF When sensor oscillation has been terminated abnormally
due to a measurement counter overflow
Writing 1
Time base counter
overflow error
RFC
n
INTF.OVTCIF
When reference oscillation has been terminated abnor-
mally due to a time base counter overflow
Writing 1
The RFC provides interrupt enable bits corresponding to each interrupt flag. An interrupt request is sent to the in-
terrupt controller only when the interrupt flag, of which interrupt has been enabled by the interrupt enable bit, is
set. For more information on interrupt control, refer to the “Interrupt Controller” chapter.