7733 datasheet(197/940 Pages) RENESAS

197 / 940 page

TIMER B

7733 Group User’s Manual

7–34

7.6 Clock timer

Timer B2 functions as a clock timer on the following condition (Refer to Table 7.6.1.):

q When the port-Xc selection bit (bit 4 at address 6C16) = “1”

q When the port-Xc selection bit = “0” and the timer B2 clock source selection bit (bit 1 at address 6D16)

= “1”

Figure 7.6.1 shows the structures of the timer B2 mode register and timer B2 register when a clock timer

is used.

Item

Count source

Count operation

Division ratio

Count start condition

Count stop condition

Interrupt request occurrence timing

Pin TB2IN’s function

Read from timer

Write to timer

Table 7.6.1 Specifications of clock timer

Specifications

fc32 (Sub clock divided by 32: f(XCIN)/32), or Main clock divided by 32: f(XIN)/32)

q Countdown

q At an underflow, the reload register’s contents is reloaded, and

counting is continued.

(n + 1)

When the count start flag is set to “1.”

When the count start flag is cleared to “0.”

At an underflow

Programmable I/O port or

φSUB output pin

A counter value can be read out by reading the timer B2 register.

s While counting is stopped

When a value is written to the timer B2 register, it is written to both

of the reload register and counter.

s While counting is in progress

When a value is written to the timer B2 register, it is written only

to the reload register. (Transferred to the counter at the next reload

time.)

n: Set value in the timer B2 register

Clocks fc32 and f(XCIN): Refer to chapter “14. CLOCK GENERATING CIRCUIT.”

Either of f(XCIN)/32 or f(XIN)/32 can be selected as the clock timer’s count source, fc32.

The way to generate f(XCIN)/32 is different from that for clocks whose source is the system clock (e.g.,

internal clock

φ, clocks f2 to f512, and so on). (Refer to chapter “14. CLOCK GENERATING CIRCUIT.”)

f(XCIN)/32 is not affected by the system clock selection bit and system clock stop bit at wait state (bits 3

and 5 at address 6C16). Therefore, in the wait mode, (Refer to chapter “11. STOP AND WAIT MODES.”)

only the clock timer can operate by itself. In other words, it is possible to supply fc32 only.

Oppositely, the way to generate f(XIN)/32 is the same as that for the system clock. Therefore, when the

system clock stop bit at wait state = “1,” fc32 is not supplied in the wait mode.

Figure 7.6.2 shows the structure of the clock timer.

7.6 Clock timer

7733 Datasheet(PDF) 197 Page - Renesas Technology Corp

7733 Datasheet(HTML) 197 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL