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EM78P468N/EM78P468L
8-Bit Microcontroller
Product Specification (V1.5) 02.15.2007
• 17
(This specification is subject to change without further notice)
6.2.8 IOCB0/CNT1PR (Counter 1 Preset Register)
(Address: 0Bh, Bit 0 of R5 = “0”)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 ~ Bit 0: These are Counter 1 buffers which user can read and write. Counter 1 is
an 8-bit down-count timer with 8-bit prescaler used to preset the counter and read the
preset value. The prescaler is set by the IOC91 register. After an interrupt, it will auto
reload the preset value.
6.2.9 IOCC0/CNT2PR (Counter 2 Preset Register)
(Address: 0Ch, Bit 0 of R5 = “0”)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 ~ Bit 0: These are Counter 2 buffers which user can read and write. Counter 2 is
an 8-bit down-count timer with 8-bit prescaler used to preset the counter and read the
preset value. The prescaler is set by IOC91 register. After an interrupt, it will reload the
preset value.
When IR output is enabled, this control register can obtain carrier frequency output.
If the Counter 2 clock source is equal to F
T
, then
Carrier frequency (Fcarrier) =
prescaler*)1+value_preset(*2
F
T
6.2.10 IOCD0/HPWTPR (High-Pulse Width Timer Preset Register)
(Address: 0Dh, Bit 0 of R5 = “0”)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 7 ~ Bit 0: These are high-pulse width timer buffers which user can read and write.
High-pulse width timer preset register is an eight-bit down-counter with 8-bit prescaler
used as IOCD0 to preset the counter and read the preset value. The prescaler is set by
the IOCA1 register. After an interrupt, it will reload the preset value.
For PWM or IR application, this control register is set as high pulse width.
If the high-pulse width timer clock source is F
T
, then
High pulse time =
T
F
)1+value_preset(*prescaler