AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 146

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

14.10.8
14.10.9
14.10.10 Output Compare Register 1 B – OCR1BH and OCR1BL
14.10.11 Output Compare Register 1 C – OCR1CH and OCR1CL
14.10.12 Output Compare Register 3 A – OCR3AH and OCR3AL
146
AT90USB64/128
Timer/Counter3 – TCNT3H and TCNT3L
Output Compare Register 1 A – OCR1AH and OCR1AL
The two Timer/Counter I/O locations (TCNTnH and TCNTnL, combined TCNTn) give direct
access, both for read and for write operations, to the Timer/Counter unit 16-bit counter. To
ensure that both the high and low bytes are read and written simultaneously when the CPU
accesses these registers, the access is performed using an 8-bit temporary High Byte Register
(TEMP). This temporary register is shared by all the other 16-bit registers.
Registers” on page 120.
Modifying the counter (TCNTn) while the counter is running introduces a risk of missing a com-
pare match between TCNTn and one of the OCRnx Registers.
Writing to the TCNTn Register blocks (removes) the compare match on the following timer clock
for all compare units.
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
R/W
R/W
R/W
R/W
R/W
R/W
TCNT1[15:8]
TCNT1[7:0]
0
7
TCNT3[15:8]
TCNT3[7:0]
0
7
OCR1A[15:8]
OCR1A[7:0]
0
7
OCR1B[15:8]
OCR1B[7:0]
0
7
OCR1C[15:8]
OCR1C[7:0]
0
7
OCR3A[15:8]
OCR3A[7:0]
0
R/W
0
6
R/W
0
6
R/W
0
6
R/W
0
6
R/W
0
6
R/W
0
R/W
0
5
R/W
0
5
R/W
0
5
R/W
0
5
R/W
0
5
R/W
0
R/W
4
R/W
4
R/W
4
R/W
4
R/W
4
R/W
0
0
0
0
0
0
R/W
0
3
R/W
0
3
R/W
0
3
R/W
0
3
R/W
0
3
R/W
0
R/W
0
2
R/W
0
2
R/W
0
2
R/W
0
2
R/W
0
2
R/W
0
R/W
0
1
R/W
0
1
R/W
0
1
R/W
0
1
R/W
0
1
R/W
0
R/W
0
0
R/W
0
0
R/W
0
0
R/W
0
0
R/W
0
0
R/W
0
See “Accessing 16-bit
TCNT1H
TCNT1L
TCNT3H
TCNT3L
OCR1AH
OCR1AL
OCR1BH
OCR1BL
OCR1CH
OCR1CL
OCR3AH
OCR3AL
7593A–AVR–02/06