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Figure 19.2.2.3 External Clock Input in External Clock Input Mode
19.3 Clock Settings
19.3.1 RFC Operating Clock
When using the RFC, the RFC operating clock TCCLK must be supplied to the RFC from the clock generator. The
TCCLK supply should be controlled as in the procedure shown below.
1. Enable the clock source in the clock generator if it is stopped (refer to "Clock Generator" in the "Power Supply,
Reset, and Clocks" chapter).
2. Set the following RFCnCLK register bits:
- RFCnCLK.CLKSRC[1:0] bits (Clock source selection)
- RFCnCLK.CLKDIV[1:0] bits (Clock division ratio selection = Clock frequency setting)
The time base counter performs counting with TCCLK set here. Selecting a higher clock results in higher conver-
sion accuracy, note, however, that the frequency should be determined so that the time base counter will not over-
flow during reference oscillation.
19.3.2 Clock Supply in SLEEP Mode
When using RFC during SLEEP mode, the RFC operating clock TCCLK must be configured so that it will keep
supplying by writing 0 to the CLGOSC.xxxxSLPC bit for the TCCLK clock source.
19.3.3 Clock Supply in DEBUG Mode
The TCCLK supply during DEBUG mode should be controlled using the RFCnCLK.DBRUN bit.
The TCCLK supply to the RFC is suspended when the CPU enters DEBUG mode if the RFCnCLK.DBRUN bit
= 0. After the CPU returns to normal mode, the TCCLK supply resumes. Although the RFC stops operating when
the TCCLK supply is suspended, the output pin and registers retain the status before DEBUG mode was entered. If
the RFCnCLK.DBRUN bit = 1, the TCCLK supply is not suspended and the RFC will keep operating in DEBUG
mode.
19.4 Operations
19.4.1 Initialization
The RFC should be initialized with the procedure shown below.
1. Configure the RFCnCLK.CLKSRC[1:0] and RFCnCLK.CLKDIV[1:0] bits. (Configure operating clock)
2. Set the following bits when using the interrupt:
- Write 1 to the interrupt flags in the RFCnINTF register.
- Set the interrupt enable bits in the RFCnINTE register to 1. (Enable interrupts)
3. Assign the RFC input/output function to the ports. (Refer to the "I/O Ports" chapter.)
S1C17W12/W13 TECHNICAL MANUAL
(Rev. 1.2)
SENBn
SENAn
REFn
RFINn
S1C17 RFC
* Leave the unused pins open.
Seiko Epson Corporation
19 R/F CONVERTER (RFC)
Square wave
Sine wave
(Clear interrupt flags)
19-3
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