M16C65 Datasheet, PDF (670/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
26. Consumer Electronics Control (CEC) Function
26.3 Operations
26.3.1 Standard Value and I/O Timing
The CEC transmission/reception is based on the count source cycle.
When outputting, an output waveform is based on the count source cycle which is closest to the CEC
standard value. When inputting, an input waveform is sampled in the count source cycle
Also, the input/output is practically performed based on the count source cycle closest to the
acceptable range or output timing.
26.3.2 Count Source
Select fC or timer A0 underflow by bits CCLK1 to CCLK0 in the CECC1 register. In either case, the
clock frequency should be 32.768kHz and oscillation allowable error should be within ± 1%. Set the
CECEN bit in the CECC1 register to 1 (CEC enabled), after the count source is selected by bits
CCLK1 and CCLK0 and when the count source is stable.
To use fC, set the PM25 bit in the PM2 register to 1 (peripheral clock fC provided). Refer to 8. “Clock
Generator” for details.
When the timer A0 underflow is used as the count source, each time timer A0 underflows the internal
signal of the timer A0 is reversed. Since this internal signal is the count source, two cycles of timer A0
underflows are one cycle of the count source. Figure 26.3 shows Count Source When Timer A0
Underflow Selected. Use the timer A0 without timer mode and gate function. Refer to 17. “Timer A”
for details.
Count source
(Timer A0 internal signal)
Timer A0
Timer A0
underflow cycle underflow cycle
Reversed by underflow
1
32.768 kHz
Figure 26.3 Count Source When Timer A0 Underflow Selected
26.3.3 CEC Input/Output
The CEC input and output share pins with the I/O port and NMI input. To use CEC input and output, set
bits as follows:
• set the PM24 bit in the PM2 register to 0 (NMI interrupt disabled)
• set bits NMIDF2 to NMIDF0 in the NMIDF register to 000b (NMI/SD filter disabled)
• set the PCR4 bit in the PCR register to 1 (CEC output enabled)
• set the PD8_5 bit in the PD8 register to 0 (input mode)
Also, the CEC input has a digital filter besides the NMI/SD filter (refer to 26.3.4 “Digital Filter”).
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
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