ADUC834 Analog Devices, ADUC834 Datasheet - Page 55

• Manufacturer Part Number: ADUC834
• Description: Precision Analog Microcontroller: 1MIPS 8052 MCU + 62kB Flash + 16/24-Bit ADC + 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC834

• Mcu Core: 8052
• Mcu Speed (mips): 1
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 4
• Other: PWM

TIMER/COUNTER 2 OPERATING 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 XXIX.
RCLK (or) TCLK
0
0
1
X
16-Bit Autoreload Mode
In Autoreload Mode, there are two options, selected by bit
EXEN2 in T2CON. If EXEN2 = 0, 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, 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 52.
REV. A
Table XXVIII. Timer 2 Operating Modes
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE "ON-CHIP PLL")
T2EX
PIN
PIN
CORE
CLK*
T2
T2EX
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE "ON-CHIP PLL")
CAP2
0
1
X
X
PIN
PIN
CORE
CLK*
T2
TRANSITION
DETECTOR
TRANSITION
DETECTOR
12
12
TR2
1
1
1
0
Figure 52. Timer/Counter 2, 16-Bit Autoreload Mode
C/ T2 = 0
C/ T2 = 1
Figure 53. Timer/Counter 2, 16-Bit Capture Mode
C/ T2 = 0
C/ T2 = 1
EXEN2
MODE
16-Bit Autoreload
16-Bit Capture
Baud Rate
OFF
EXEN2
CONTROL
TR2
CONTROL
TR2
CONTROL
RELOAD
CONTROL
CAPTURE
RCAP2L
(8 BITS)
–55–
TL2
RCAP2L
(8 BITS)
TL2
16-Bit Capture Mode
In the Capture Mode, there are again two options, selected by bit
EXEN2 in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer or
counter that, upon overflowing, sets bit TF2, the Timer 2 over-
flow bit, which can be used to generate an interrupt. If EXEN2 = 1,
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; EXF2, like TF2, can gener-
ate an interrupt. The Capture Mode is illustrated in Figure 53.
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. However, in
this mode, 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.
RCAP2H
(8 BITS)
TH2
RCAP2H
(8 BITS)
TH2
EXF2
TF2
EXF2
TF2
TIMER
INTERRUPT
TIMER
INTERRUPT
ADuC834