HC705V8GRSSLASHD datasheet(90/172 Pages) NXP

90 / 172 page

SECTION 11: 16-BIT TIMER

Page 79

MC68HC705V8 Specification Rev. 2.1

11.4.6

OLVL - Output Level

Value of output level is clocked into output level register by the next successful

output compare and will appear on the TCMP pin

1 - High output

0 - Low output

11.5

TIMER STATUS REGISTER (TSR) - $13

The TSR is a read-only register containing three status flag bits.

Figure 11-4:

Timer Status Register - $13

11.5.1

ICF - Input Capture Flag

1 - Flag set when selected polarity edge is sensed by input capture edge

detector

0 - Flag cleared when TSR and input capture low register ($15) are accessed

Reset clears this bit.

11.5.2

OCF - Output Compare Flag

1 - Flag set when output compare register contents match the free-running

counter contents

0 - Flag cleared when TSR and output compare low register ($17) are

accessed

Reset clears this bit.

11.5.3

TOF - Timer Overflow Flag

1 - Flag set when free-running counter transition from $FFFF to $0000 occurs

0 - Flag cleared when TSR and counter low register ($19) are accessed

Reset clears this bit.

11.5.4

Bits 0-4 - Not used

Always read zero.

Accessing the timer status register satisfies the first condition required to clear status bits.

The remaining step is to access the register corresponding to the status bit.

A problem can occur when using the timer overflow function and reading the free-running

counter at random times to measure an elapsed time. Without incorporating the proper

precautions into software, the timer overflow flag could unintentionally be cleared if:

1. The timer status register is read or written when TOF is set, and

2. The MSB of the free-running counter is read but not for the purpose of

servicing the flag.

ICF

OCF

TOF

00000

RESET

$13

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

HC705V8GRS/D Datasheet(PDF) 90 Page - NXP Semiconductors

HC705V8GRS/D Datasheet(HTML) 90 Page - NXP Semiconductors

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