Renesas M16C/64C User Manual page 828

M16C/64C Group
32.20 Notes on CEC
32.20.1 Registers and Bit Operation
The registers and bits of the CEC function are synchronized with the count source. Therefore, the
internal circuit starts to operate from the next count source timing, while the values of the register are
changed immediately after rewriting the register.
When rewriting the same bit successively or reading the bit changed under the influence of another bit,
wait for one or more cycles of the count source.
Example: when rewriting the same bit successively
(1) Change the bit to 0.
(2) Wait for one or more cycles of the count source.
(3) Change the same bit to 1.
Example: when reading the bit rewritten under the influence of another bit
(after reception is disabled, to ensure that the CRERRFLG bit in the CECFLG register becomes 0 (no
reception error detected)).
(1) Set the CRXDEN bit in the CECC3 register to 0 (reception disabled)
(2) Wait for one or more cycles of the count source.
(3) Read the CRERRFLG bit in the CECFLG register.
32.20.2 VIH of the CEC pin
VIH of the CEC pin does not meet the CEC standard value. Apply VIH to the CEC pin or use the CEC
external circuit shown in Figure 32.12 "CEC External Circuit" to change the CEC pin input voltage to
VIH of the CEC pin or above.
P8_5/NMI/SD/CEC
Figure 32.12 CEC External Circuit
R01UH0092EJ0110 Rev.1.10
Jul 31, 2012
VCC1
VCC1
FET
32. Usage Notes
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