Rainbow Electronics ATtiny861_V - Manual (Page 115)

115
2588B–AVR–11/06
ATtiny261/461/861
that the Data Direction Register (DDR) bit corresponding to the OC1B pin must be set in order to
enable the output driver.
The function of the COM1B1:0 bits depends on the PWM1B and WGM10 bit settings. Table 16-
11 shows the COM1B1:0 bit functionality when the PWM1B bit is set to Normal Mode (non-
PWM).
Table 16-12 shows the COM1B1:0 bit functionality when the PWM1B and WGM10 bits are set to
Fast PWM Mode.
Table 16-13 shows the COM1B1:0 bit functionality when the PWM1B and WGM10 bits are set to
Phase and Frequency Correct PWM Mode.
• Bit 3 - FOC1A: Force Output Compare Match 1A
The FOC1A bit is only active when the PWM1A bit specify a non-PWM mode.
Writing a logical one to this bit forces a change in the Waveform Output (OCW1A) and the Out-
put Compare pin (OC1A) according to the values already set in COM1A1 and COM1A0. If
COM1A1 and COM1A0 written in the same cycle as FOC1A, the new settings will be used. The
Force Output Compare bit can be used to change the output pin value regardless of the timer
Table 16-11. Compare Output Mode, Normal Mode (non-PWM)
COM1B1..0 OCW1B Behaviour OC1B Pin OC1B Pin
00 Normal port operation. Disconnected Disconnected
01 Toggle on Compare Match. Connected Disconnected
10 Clear on Compare Match. Connected Disconnected
11 Set on Compare Match. Connected Disconnected
Table 16-12. Compare Output Mode, Fast PWM Mode
COM1B1..0 OCW1B Behaviour OC1B Pin OC1B Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match.
Set when TCNT1 = 0x000.
Connected Connected
10
Cleared on Compare Match.
Set when TCNT1 = 0x000.
Connected Disconnected
11
Set on Compare Match.
Cleared when TCNT1 = 0x000.
Connected Disconnected
Table 16-13. Compare Output Mode, Phase and Frequency Correct PWM Mode
COM1B1..0 OCW1B Behaviour OC1B Pin OC1B Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Connected
10
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Disconnected
11
Set on Compare Match when up-counting.
Cleared on Compare Match when down-counting.
Connected Disconnected