AT90S2313
32
•
Bits 7,6 - COM1A1, COM1A0: Compare Output Mode1, bits 1 and 0
The COM1A1 and COM1A0 control bits determine any output pin action following a compare match in Timer/Counter1.
Any output pin actions affect pin OC1 - Output Compare pin 1 (PB3). This is an alternative function to the I/O port, and the
corresponding direction control bit must be set (one) to control an output pin. The control configuration is shown in Table 8.
Note: In PWM mode, these bits have a different function. Refer to Table 12 for a detailed description.
• Bits 5..2 - Res: Reserved bits
These bits are reserved bits in the AT90S2313 and always read zero.
•
Bits 1,0 - PWM11, PWM10: Pulse Width Modulator Select Bits
These bits select PWM operation of Timer/Counter1 as specified in Table 9. This mode is described on page 35.
Timer/Counter1 Control Register B - TCCR1B
•
Bit 7 - ICNC1: Input Capture1 Noise Canceler (4 CKs)
When the ICNC1 bit is cleared (zero), the input capture trigger noise canceler function is disabled. The input capture is trig-
gered at the first rising/falling edge sampled on the ICP - input capture pin - as specified. When the ICNC1 bit is set (one),
four successive samples are measures on the ICP - input capture pin, and all samples must be high/low according to the
input capture trigger specification in the ICES1 bit. The actual sampling frequency is the XTAL clock frequency.
•
Bit 6 - ICES1: Input Capture1 Edge Select
While the ICES1 bit is cleared (zero), the Timer/Counter1 contents are transferred to the Input Capture Register - ICR1 - on
the falling edge of the input capture pin - ICP. While the ICES1 bit is set (one), the Timer/Counter1 contents are transferred
to the Input Capture Register - ICR1 - on the rising edge of the input capture pin - ICP.
•
Bits 5, 4 - Res: Reserved bits
These bits are reserved bits in the AT90S2313 and always read zero.
Table 8. Compare 1 Mode Select
COM1A1 COM1A0 Description
0 0 Timer/Counter1 disconnected from output pin OC1
0 1 Toggle the OC1 output line.
1 0 Clear the OC1 output line (to zero).
1 1 Set the OC1 output line (to one).
Table 9. PWM Mode Select
PWM11 PWM10 Description
0 0 PWM operation of Timer/Counter1 is disabled
0 1 Timer/Counter1 is an 8-bit PWM
1 0 Timer/Counter1 is a 9-bit PWM
1 1 Timer/Counter1 is a 10-bit PWM
Bit 7 6 5 4 3 2 1 0
$2E ($4E) ICNC1 ICES1 - - CTC1 CS12 CS11 CS10 TCCR1B
Read/Write R/W R/W R R R/W R/W R/W R/W
Initial value 0 0 0 0 0 0 0 0
To Next Page
Loading...
