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20. R/F Converter (RFC)
20.1. Overview
The RFC is a CR oscillation type A/D converter (R/F converter).
The features of the RFC are listed below.
•
Converts the sensor resistance into a digital value by performing CR oscillation and counting the
oscillation clock.
•
Achieves high-precision measurement system with low errors by oscillating the reference resistor and
the sensor in the same conditions to obtain the difference between them.
•
Includes a 24-bit measurement counter to count the oscillation clocks.
•
Includes a 24-bit time base counter to count the internal clock for equalizing the measurement time
between the reference resistor and the sensor.
•
Supports DC bias resistive sensors and AC bias resistive sensors.
(A thermometer/hygrometer can be easily implemented by connecting a thermistor or a humidity
sensor and a few passive elements (resistor and capacitor).)
•
Allows measurement (counting) by inputting external clocks.
•
Provides an output and continuous oscillation function for monitoring the oscillation frequency.
•
Can generate reference oscillation completion, sensor (A and B) oscillation completion,
measurement counter overflow error, and time base counter overflow error interrupts.
Figure 20.1.1 shows the RFC configuration.
Item
Number of channels
CPU core
Clock generator
S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
Table 20.1.1 RFC Channel Configuration of S1C31D50
1 channel (Ch.0)
* Can only be used in DC oscillation mode for resistive sensor measurements.
RFC Ch.n
OVTCIE
Interrupt
OVMCIE
control circuit
ESENBIE
ESENAIE
EREFIE
CLKSRC[1:0]
CLKDIV[1:0]
DBRUN
MODEN
Counter
control circuit
CONEN
EVTEN
CR oscillation
control circuit
SMODE[1:0]
Figure 20.1.1 RFC Configuration
Seiko Epson Corporation
S1C31D50
OVTCIF
OVMCIF
ESENBIF
ESENAIF
EREFIF
Time base counter
TC[23:0]
1/2
Measurement counter
MC[23:0]
SSENB
SSENA
Oscillation
circuit
SREF
RFCLKMD
RFCLKOn
RFINn
REFn
SENAn
SENBn
20-1
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