Rainbow-electronics ATmega8515L Manual de usuario descargar pdf (Pagina 116)

116

ATmega8515(L)

2512A–AVR–04/02

16-bit Timer/Counter

Timer/Counter1 Control

• Bit 7:6 – COM1A1:0: Compare Output Mode for Channel A

• Bit 5:4 – COM1B1:0: Compare Output Mode for Channel B

The COM1A1:0andCOM1B1:0 control the Output Compare pins(OC1A andOC1B

respectively) behavior. If one orboth of the COM1A1:0 bits are writtentoone, the OC1A

output overrides thenormalport functionality of the I/Opin it isconnected to. If one or

both of the COM1B1:0 bit are written to one, the OC1B output overrides thenormalport

functionality of the I/Opin it isconnected to. However, note that the

Data Direction Reg-

ister

(DDR)bit correspondingtothe OC1A orOC1Bpin must be set in order to enable

the output driver.

When the OC1A orOC1B isconnected to the pin, the function of the COM1x1:0 bits is

dependent of the WGM13:0 bitssetting. Table50shows the COM1x1:0 bit functionality

when the WGM13:0 bits are set to a normal or a CTC mode (non-PWM).

Table51shows the COM1x1:0 bit functionalitywhen the WGM13:0 bits are set to the

fastPWM mode.

Note: 1. A specialcaseoccurs when OCR1A/OCR1B equals TOPandCOM1A1/COM1B1is

set. Inthiscasethe comparematch is ignored, but the set orclear isdone at TOP.

See “FastPWM Mode” on page 108. for more details.

Table52shows the COM1x1:0 bit functionalitywhen the WGM13:0 bits are set to the

phase corrector the phaseandfrequency correct, PWM mode.

Bit 76543 210

COM1A1 COM1A0 COM1B1 COM1B0 FOC1A FOC1B WGM11 WGM10 TCCR1A

Read/Write R/W R/W R/W R/WW WR/W R/W

Initial Value0 0 0 0 0000

Table 50. Compare Output Mode, non-PWM

COM1A1/

COM1B1

COM1A0/

COM1B0 Description

00Normalportoperation,OC1A/OC1Bdisconnected.

0 1 Toggle OC1A/OC1B on comparematch.

10ClearOC1A/OC1B on comparematch (Set output to lowlevel).

11Set OC1A/OC1B on comparematch (Set output to highlevel).

Table 51. Compare Output Mode,FastPWM

(1)

COM1A1/

COM1B1

COM1A0/

COM1B0 Description

00Normalportoperation,OC1A/OC1Bdisconnected.

01WGM13=0:Normalportoperation,OC1A/OC1Bdisconnected.

WGM13=1: Toggle OC1A on comparematch, OC1Breserved.

10ClearOC1A/OC1B on comparematch, set OC1A/OC1B at TOP.

11Set OC1A/OC1B on comparematch, clearOC1A/OC1B at TOP.

1 2 ... 111 112 113 114 115 116 117 118 119 120 121 ... 222 223

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