18 R/F CONVERTER (RFC)
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
18-9
TECHNICAL MANUAL (Rev. 1.0)
Bit 7
CONEN
This bit disables the automatic CR oscillation stop function to enable continuous oscillation function.
1 (R/W): Enable continuous oscillation
0 (R/W): Disable continuous oscillation
For more information, refer to “CR Oscillation Frequency Monitoring Function.”
Bit 6
EVTEN
This bit enables external clock input mode (event counter mode).
1 (R/W): External clock input mode
0 (R/W): Normal mode
For more information, refer to “Operating Modes.”
Note
: Do not input an external clock before the RFC
n
CTL.EVTEN bit is set to 1. The RFIN
n
pin is
pulled down to V
SS
level when the port function is switched for the R/F converter.
Bits 5–4
SMODE[1:0]
These bits configure the oscillation mode. For more information, refer to “Operating Modes.”
Table 18.6.2 Oscillation Mode Selection
RFCnCTL.SMODE[1:0] bits
Oscillation mode
0x3, 0x2
Reserved
0x1
AC oscillation mode for resistive sensor measurements
0x0
DC oscillation mode for resistive sensor measurements
Bits 3–1
Reserved
Bit 0
MODEN
This bit enables the RFC operations.
1 (R/W): Enable RFC operations (The operating clock is supplied.)
0 (R/W): Disable RFC operations (The operating clock is stopped.)
Note
: If the RFC
n
CTL.MODEN bit is altered from 1 to 0 during R/F conversion, the counter value
being converted cannot be guaranteed. R/F conversion cannot be resumed.
RFC Ch.
n
Oscillation Trigger Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
RFCnTRG
15–8 –
0x00
–
R
–
7–3 –
0x00
–
R
2
SSENB
0
H0
R/W
1
SSENA
0
H0
R/W
0
SREF
0
H0
R/W
Bits 15–3 Reserved
Bit 2
SSENB
This bit controls CR oscillation for sensor B. This bit also indicates the CR oscillation status.
1 (W):
Start oscillation
0 (W):
Stop oscillation
1 (R):
Being oscillated
0 (R):
Stopped
Note
: Writing 1 to the RFC
n
TRG.SSENB bit does not start oscillation when the RFC
n
CTL.
SMODE[1:0] bits = 0x1 (AC oscillation mode for resistive sensor measurements).
Bit 1
SSENA
This bit controls CR oscillation for sensor A. This bit also indicates the CR oscillation status.
1 (W):
Start oscillation
0 (W):
Stop oscillation
1 (R):
Being oscillated
0 (R):
Stopped