S1C63656 TECHNICAL MANUAL
EPSON
115
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (R/f Converter)
4.14.4 Interrupt function
The R/f converter has a function which allows interrupt to occur after R/f conversion.
When the measurement counter is counted up to 00000H, both counters stop counting. The interrupt
factor flag IRFB is set to "1" at the rising edge of the OSC1 clock immediately after RFRUNR is set to "0"
and an interrupt occurs.
When the time base counter is counted down to 00000H, both counters stop counting. The interrupt
factor flag IRFM is set to "1" at the rising edge of the OSC1 clock immediately after the RFRUNS register
is set to "0" and an interrupt occurs.
If the measurement counter overflows during counting of the sensor oscillation, or the time base counter
overflows during counting of the reference resistance oscillation, the interrupt factor flag IRFM or IRFB is
also set to "1". These interrupt factors allow masking by the interrupt mask registers EIRFM and EIRFB.
When the EIRFM/EIRFB has been set at "1", an interrupt occurs in the CPU. When the EIRFM/EIRFB is
set at "0", no interrupt will occur in the CPU even if the interrupt factor flag is set to "1". The interrupt
factor flag is reset to "0" by writing "1".
Timing of interrupt by the R/f converter is shown in Figures 4.14.4.1 to 4.14.4.4.
n
0
FFFFCH FFFFBH
n+1
n+2
n+3
FFFFD
FFFFEH FFFFFH
0
x+3
x+2
x+1
x
FFFFFH FFFFEH
Oscillation by reference resistance
Input clock
RFRUNR register
Time base counter
Measurement counter clock
Measurement counter
IRFB
Interrupt request
Count-down
FFFFDH
Fig. 4.14.4.1 Reference oscillate completion interrupt
0
x
x+4
x+5
1
2
3
m-3
m-2
m-1
m
FFFFEH FFFFFH
0
x+1
x+2
Oscillation by sensor resistance
Input clock
RFRUNS register
Time base counter
Measurement counter clock
Measurement counter
IRFM
Interrupt request
Count-up
x+3
Fig. 4.14.4.2 Sensor oscillate completion interrupt
0
x
x+4
x+5
1
2
3
FFFFDH FFFFEH FFFFFH
0
y-2
y-1
y
x+1
x+2
x+3
Oscillation by sensor resistance
Input clock
RFRUNS register
Time base counter
Measurement counter clock
Measurement counter
OVMC, IRFM
Interrupt request
Count-up
Fig. 4.14.4.3 Measurement counter overflow interrupt