Uart baud rate register – ubrr, Analog comparator – Rainbow Electronics AT90S2313 User Manual
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48
AT90S2313
0839I–AVR–06/02
UART Baud Rate Register –
UBRR
The UBRR Register is an 8-bit read/write register that specifies the UART Baud Rate
according to the formula on the previous page.
Analog Comparator
The Analog Comparator compares the input values on the positive input AIN0 (PB0) and
the negative input PB1(AIN1). When the voltage on the positive input PB0 (AIN0) is
higher than the voltage on the negative input PB1 (AIN1), the Analog Comparator Out-
put, ACO is set (one). The comparator’s output can be set to trigger the Timer/Counter1
Input Capture function. In addition, the comparator can trigger a separate interrupt
exclusive to the Analog Comparator. The user can select interrupt triggering on compar-
ator output rise, fall or toggle. A block diagram of the comparator and its surrounding
logic is shown in Figure 37.
Figure 37. Analog Comparator Block Diagram
Analog Comparator Control
and Status Register – ACSR
• Bit 7 – ACD: Analog Comparator Disable
When this bit is set (one), the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the Analog Comparator. This will reduce power con-
sumption in active and Idle modes. When changing the ACD bit, the Analog Comparator
Interrupt must be disabled by clearing the ACIE bit in ACSR. Otherwise an interrupt can
occur when the bit is changed.
• Bit 6 – Res: Reserved Bit
This bit is a reserved bit in the AT90S2313 and will always read as zero.
Bit
7
6
5
4
3
2
1
0
$09 ($29)
MSB
LSB
UBRR
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$08 ($28)
ACD
–
ACO
ACI
ACIE
ACIC
ACIS1
ACIS0
ACSR
Read/Write
R/W
R
R
R/W
R/W
R/W
R/W
R/W
Initial value
0
0
N/A
0
0
0
0
0