7480 datasheet(110/337 Pages) RENESAS

110 / 337 page

7480 Group and 7481 Group User's Manual

1-93

1.12 Timer X and Timer Y

HARDWARE

Reads from Timers

• When the high-order byte of an operating timer is read, the low-order byte is set in the latch for

reading. Therefore, the read value of the low-order byte retains the value at the time the high-order

byte is being read.

• In the count operation, the contents of each timer are decremented by 1 at every rising edge of

the count source, while the contents of each timer are transferred to the latch for reading by falling

edge, so that the read value of the timer may be different from its real value.

Figure 1.12.28 shows an operation in timer X or timer Y at reads.

Figure 1.12.28 Operation in Timer X or Timer Y at Reads

(2)

In Event Count Mode

The inverted signal of input to a CNTR pin is used as the count source when a CNTR edge selection

bit of the edge polarity selection register is ‘1’.

Keep the frequency of the CNTR pin input used as the count source f(XIN)/4 or less.

(3)

In Pulse Output Mode

When the timer X or Y write control bit is ‘0’, the CNTR pin output is initialized to the following levels

by a write to the timer:

• HIGH when the CNTR edge selection bit is ‘0’.

• LOW when the CNTR edge selection bit is ‘1’.

When the timer X or Y write control bit, however, is ‘1’, the CNTR pin output level cannot be

initialized by a write to the timer.

The output level of a CNTR pin is inverted when the CNTR edge polarity selection bit is switched.

(4)

In Pulse Period Measurement Mode and Pulse Width Measurement Mode

Do not write to timers in these modes; otherwise the last measured value in the timer latch will be

changed by this write.

When a timer is read, the read value is the contents of the timer latch (the last measured value).

(5)

In Programmable Waveform Generation Mode

When the timer X or Y operation mode bits, which are set to other modes, are switched to the

programmable waveform generation mode, the CNTR pin outputs are initialized to LOW.

When the timer X or Y trigger selection bit is ‘1’, keep the trigger widths input to the INT pins 250ns

or more.

Count source

High-order of timer is read (Read value: ‘0116’)

In this case, the low-order read value ‘0116’ is

written to latch for reading.

Low-order of timer is read (Read value: ‘0116’)

Contents of timer

Read value of timer

010016

00FF16

00FE16

010116

010216

010016

00FF16

00FE16

00FD16

010116

7480 Datasheet(PDF) 110 Page - Renesas Technology Corp

7480 Datasheet(HTML) 110 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