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CHAPTER 12 U-TIMER (16-bit Timer for UART Baud Rate Generation)
12.1
Overview
The U-TIMER is a 16-bit timer used to generate the baud rate for the UART. Use a
combination of a chip operating frequency and a reload value of the U-TIMER to specify
a baud rate. Also, since it generates an interrupt by count underflow, it can be used as
an interval timer.
The MB91260B series have three built-in channels for this timer. When used as an
interval timer, two pairs of U-TIMERs can be cascaded to count a maximum interval of
32
× φ.
2
Only a combination of ch.0 and ch.1, and a combination of ch.0 and ch.2 can be
connected in cascade mode.
■ Register List
15
■ Block Diagram
φ
(Peripheral clock)
underflow U-TIMER 1
298
8 7
UTIM0 to UTIM2
UTIMR0 to UTIMR2
Figure 12.1-1 Block Diagram for U-TIMER
15
UTIMR0 to UTIMR2 (reload register)
15
UTIM0 to UTIMR2 (timer)
MUX Channel
0 only
21UTIMC0 to UTIMC2
load
clock
underflow
0
(R)
(W)
(R/W)
0
0
control
F/F
to UART
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