ADUC812 Analog Devices, ADUC812 Datasheet - Page 34

• Manufacturer Part Number: ADUC812
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 8kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC812

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 256Bytes
• Gpio Pins: 34
• Adc # Channels: 8

ADuC812
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 XVIII.
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
reload 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 30.
Table XVIII. TIMECON SFR Bit Designations
T2EX
T2EX
PIN
PIN
PIN
PIN
CORE
CORE
CAP2
0
1
X
X
CLK
T2
CLK
T2
TRANSITION
TRANSITION
DETECTOR
DETECTOR
12
12
TR2
1
1
1
0
Figure 30. Timer/Counter 2, 16-Bit Autoreload Mode
Figure 31. 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
CAPTURE
RELOAD
–34–
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 that, upon overflowing, sets bit TF2,
the Timer 2 overflow bit, that 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
registers 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 31.
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 inter-
rupts will not occur, so they do not have to be disabled. In this
mode however, the EXF2 flag 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. E