FUJITSU MB91F109 FR30 - Manual (Page 264)

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CHAPTER 9 U-TIMER
9.1 Overview of U-TIMER
The U-TIMER is a 16-bit timer that generates a UART baud rate. Combining the chip
operating frequency and U-TIMER reload value can generate a desired baud rate.
Since a count underflow causes an interrupt, the U-TIMER can also be used as an
interval timer.
The MB91F109 contains three channels of U-TIMER. When the U-TIMER is used as an
interval timer, two channels (0 and 1) of U-TIMER can be cascaded to count up to 2
32
×
φφφφ
interval.
■ U-TIMER Registers
Figure 9.1-1 shows the U-TIMER registers.
Figure 9.1-1 U-TIMER Registers
■ U-TIMER Block Diagram
Figure 9.1-2 is a U-TIMER block diagram.
Figure 9.1-2 U-TIMER Block Diagram
15 8 7 0
UTIM (R)
UTIMR (W)
UTIMC (R/W)
15 0
UTIMR(reload register)
15 load 0
UTIM (timer)
clock underflow
control
f.f. to UART
underflow
U-TIMER1
(Peripheral clock)
(Channel 0 only)
MUX