ADUC831 Analog Devices, ADUC831 Datasheet - Page 54

• Manufacturer Part Number: ADUC831
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 62kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC831

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 8
• Other: PWM

ADuC831
Timer/Counter Operation Modes
The following paragraphs describe the operating modes for
Timer/Counter 2. The operating modes are selected by bits in the
T2CON SFR as shown in Table XXII.
RCLK (or) TCLK
0
0
1
X
16-Bit Autoreload Mode
In Autoreload mode, there are two options, which are selected
by bit EXEN2 in T2CON. If EXEN2 = 0, then when Timer 2
rolls over it not only sets TF2, but also causes the Timer 2 registers
to be reloaded with the 16-bit value in registers RCAP2L and
RCAP2H, which are preset by software. If EXEN2 = 1, then
Timer 2 still performs the above, but with the added feature that
a 1-to-0 transition at external input T2EX will also trigger the
16-bit reload and set EXF2. The Autoreload mode is illustrated
in Figure 49.
Table XXII. T2CON Operating Modes
T2EX
T2EX
CAP2
0
1
X
X
PIN
PIN
PIN
PIN
CORE
CORE
T2
CLK
T2
CLK
TRANSITION
TRANSITION
DETECTOR
DETECTOR
12
12
TR2
1
1
1
0
Figure 49. Timer/Counter 2, 16-Bit Autoreload Mode
Figure 50. Timer/Counter 2, 16-Bit Capture Mode
C/ T2 = 0
C/ T2 = 1
C/ T2 = 0
C/ T2 = 1
Mode
16-Bit Autoreload
16-Bit Capture
Baud Rate
OFF
EXEN2
EXEN2
CONTROL
CONTROL
TR2
TR2
CONTROL
CONTROL
RELOAD
CAPTURE
–54–
RCAP2L
RCAP2L
(8 BITS)
(8 BITS)
TL2
TL2
16-Bit Capture Mode
In the Capture mode, there are again two options, which are
selected by bit EXEN2 in T2CON. If EXEN2 = 0, then Timer 2
is a 16-bit timer or counter which, upon overflowing, sets bit TF2,
the Timer 2 overflow bit, which can be used to generate an inter-
rupt. If EXEN2 = 1, then Timer 2 still performs the above, but
a l-to-0 transition on external input T2EX causes the current value
in the Timer 2 registers, TL2 and TH2, to be captured into regis-
ters RCAP2L and RCAP2H, respectively. In addition, the
transition at T2EX causes bit EXF2 in T2CON to be set, and
EXF2, like TF2, can generate an interrupt. The Capture mode
is illustrated in Figure 50.
The baud rate generator mode is selected by RCLK = 1 and/or
TCLK = 1.
In either case, if Timer 2 is being used to generate the baud
rate, the TF2 interrupt flag will not occur. Therefore, Timer 2
interrupts will not occur so they do not have to be disabled. In
this mode the EXF2 flag, however, can still cause interrupts and
this can be used as a third external interrupt.
Baud rate generation will be described as part of the UART
serial port operation in the following pages.
RCAP2H
RCAP2H
(8 BITS)
(8 BITS)
TH2
TH2
EXF2
EXF2
TF2
TF2
TIMER
INTERRUPT
TIMER
INTERRUPT
REV. 0