Epson S1C63666 Technical Manual page 129

MC0–MC19: Measurement counter (FF92H–FF96H)
The measurement counter counts up according to the CR oscillation clock. It permits writing and reading
on a 4-bit basis.
The complement of the number of clocks to be counted by the oscillation of the reference resistance must
be entered in this counter prior to reference oscillation. When the counter reaches 00000H due to over-
flow, the oscillation of the reference resistance stops.
When converting a sensor oscillation, 00000H must be set in this register (it is unnecessary when it is
done immediately after a reference oscillation has completed). The sensor oscillation and measurement
counter stop when the time base counter overflows. Number of clocks counted by the sensor oscillation
can be evaluated from the value indicated by the counter when it stops. Calculate the target value by
processing the above counted number according to the program.
Measurable range and the overflow of the counter must be taken into account when setting an initial
value to be entered prior to R/f conversion.
At initial reset, this counter is undefined.
TC0–TC19: Time base counter (FF97H–FF9BH)
Writing and reading is possible on a 4-bit basis by the time base counter that is used to adjust the CR
oscillation time between the reference resistance and the sensor.
The time base counter counts down during oscillation of the reference resistance and counts up to 00000H
during oscillation of the sensor.
00000H needs to be entered in the counter prior to a reference oscillation in order to adjust the CR
oscillating time (number of clocks) of both counts. The counter value after a reference oscillation has
completed should be read from this register and save it in the memory. The saved value should be set in
this counter before starting a sensor oscillation.
At initial reset, this counter is undefined.
SENSEL: Sensor selection register (FF90H•D0)
Selects the sensor to be converted.
When "1" is written: Sensor 1
When "0" is written: Sensor 0
Reading: Valid
When "1" is written to SENSEL, sensor 1 is selected for R/f conversion and when "0" is written, sensor 0 is
selected.
At initial reset, this register is set to "0".
RFRUNR: Reference oscillation RUN/STOP control (FF91H•D1)
Starts R/f conversion for the reference resistance and indicates the operating (RUN/STOP) status.
When "1" is written: R/f conversion starts
When "0" is written: R/f conversion stops
When "1" is read: RUN status
When "0" is read: STOP status
When "1" is written to RFRUNR, R/f conversion for the reference resistance starts. The register remains at
"1" during R/f conversion and is set to "0" when R/f conversion is terminated.
When "0" is written to RFRUNR during R/f conversion, R/f conversion is paused.
At initial reset, this register is set to "0".
S1C63666 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (R/f Converter)
EPSON
119