PixArt Imaging Inc.

PAC107

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PixArt Imaging Inc.

E-mail:

fae_service@pixart.com.tw

V1.4, Aug, 2005

then initiated by a detected high-to-low transition on the RXD pin.

Baud Rates

Baud Rate for Mode 0:

The baud rate for mode 0 id fixed at Fosc/12.

Baud Rtes for Mode 2

Mode 2 has two baud rates, which are selected by the SMOD bit in the PCON register. The

following expression defines the baud rate:

Baud Rates for Modes 1 and 3

In modes 1 and 3, the baud rate is generated by overflow of timer (default) and/or timer 2.

You may select either or both timer(s) to generate the baud rate(s) for the transmitter and/or

the receiver.

Timer 1 Generated Baud Rates (Mode 1 and 3)

Timer 1 is the default baud rate generator for the transmitter and the receiver in modes 1

and 3. The baud rate is determined by the timer 1 overflow rate and the value of SMOD, as

shown in the following formula:

Selecting Timer 1 as the Baud Rate Generator

To select timer 1 as the baud rate generator:

•

Disable the timer interrupt by clearing the IE0 register.

•

Configure timer 1 as a timer or an event counter (set or clear the C/T bit in the

TMOD register).

•

Select timer mode 0-3 by programming the M1, M0 bits in the TMOD register.

Sreial I/O Mode 2 Baud Rate

2

SMOD

Fosc

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Sreial I/O Mode 1 and 3 Baud Rate

2

SMOD

Timer 1 Onerflow Rate

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