ATMEGA640 datasheet(138/436 Pages) MICROCHIP

138 / 436 page

138

ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

The following code examples show how to do an atomic write of the TCNTn Register contents. Writing any of the

OCRnA/B/C or ICRn Registers can be done by using the same principle.

Note:

1. See “About Code Examples” on page 10.

The assembly code example requires that the r17:r16 register pair contains the value to be written to TCNTn.

17.3.1

Reusing the Temporary High Byte Register

If writing to more than one 16-bit register where the high byte is the same for all registers written, then the high byte

only needs to be written once. However, note that the same rule of atomic operation described previously also

applies in this case.

17.4 Timer/Counter Clock Sources

The Timer/Counter can be clocked by an internal or an external clock source. The clock source is selected by the

Clock Select logic which is controlled by the Clock Select (CSn2:0) bits located in the Timer/Counter control Regis-

ter B (TCCRnB). For details on clock sources and prescaler, see “Timer/Counter 0, 1, 3, 4, and 5 Prescaler” on

page 164.

Assembly Code Example(1)

TIM16_WriteTCNTn:

; Save global interrupt flag

r18,SREG

; Disable interrupts

cli

; Set TCNTn to r17:r16

out

TCNTnH,r17

out

TCNTnL,r16

; Restore global interrupt flag

out

SREG,r18

ret

C Code Example(1)

void

TIM16_WriteTCNTn( unsigned int i )

{

unsigned char

sreg;

unsigned int

/* Save global interrupt flag */

sreg = SREG;

/* Disable interrupts */

__disable_interrupt();

/* Set TCNTn to i */

TCNTn = i;

/* Restore global interrupt flag */

SREG = sreg;

}

ATMEGA640 датащи(PDF) 138 Page - Microchip Technology

ATMEGA640 датащи(HTML) 138 Page - Microchip Technology

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

датащи скачать

ссылки URL