EVAL-ADUC831QSZ Analog Devices Inc, EVAL-ADUC831QSZ Datasheet - Page 57

• Manufacturer Part Number: EVAL-ADUC831QSZ
• Description: KIT DEV FOR ADUC831 QUICK START
• Manufacturer: Analog Devices Inc
• Series: QuickStart™ Kitr
• Type: MCUr

Specifications of EVAL-ADUC831QSZ

• Contents: Evaluation Board, Power Supply, Cable, Software and Documentation
• Silicon Manufacturer: Analog Devices
• Core Architecture: 8051
• Silicon Core Number: ADuC831
• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Mcu Supported Families: ADUC8xx
• Development Tool Type: Hardware - Eval/Demo Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ADuC831
• Lead Free Status / Rohs Status: Compliant
• Other names: EVAL-ADUC831QS; EVAL-ADUC831QS

Timer 1 Generated Baud Rates
When Timer 1 is used as the baud rate generator, the baud rates
in Modes 1 and 3 are determined by the Timer 1 overflow rate
and the value of SMOD as follows:
The Timer 1 interrupt should be disabled in this application. The
Timer itself can be configured for either timer or counter opera-
tion, and in any of its three running modes. In the most typical
application, it is configured for timer operation in the Autoreload
mode (high nibble of TMOD = 0010 binary). In that case, the baud
rate is given by the formula:
Table XXIV shows some commonly used baud rates and how they
might be calculated from a core clock frequency of 11.0592 MHz
and 12 MHz. Generally speaking, a 5% error is tolerable using
asynchronous (start/stop) communications.
Ideal
Baud
9600
19200
9600
2400
Timer 2 Generated Baud Rates
Baud rates can also be generated using Timer 2. Using Timer 2 is
similar to using Timer 1 in that the timer must overflow 16 times
before a bit is transmitted/received. Because Timer 2 has a 16-bit
REV. 0
Table XXIV. Commonly-Used Baud Rates, Timer 1
(
Modes
2
Core
CLK
(MHz)
12
11.0592
11.0592
11.0592
SMOD
(
Modes
2
SMOD
1
/
NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12.
NOTE: AVAILABILITY OF ADDITIONAL
EXTERNAL INTERRUPT
and
32
TRANSITION
T2EX
DETECTOR
PIN
PIN
1
1
1
0
0
CORE
/
) (
T2
SMOD TH1-Reload Actual
Value
CLK
32
×
3
and
Baud Rate =
Core Clock / (
) (Timer Overflow Rate)
×
3
Baud Rate =
2
Value
–7
–3
–3
–12 (F4H)
1
(FDH)
(F9H)
(FDH)
C/ T2 = 0
C/ T2 = 1
12
×
EXEN2
[
256
CONTROL
CONTROL
Figure 53. Timer 2, UART Baud Rates
Baud
8929
19200
9600
2400
– TH
TR2
1
EXF 2
]))
%
Error
7
0
0
0
RCAP2L
(8 BITS)
TL2
TIMER 2
INTERRUPT
–57–
RCAP2H
(8 BITS)
Autoreload mode, a wider range of baud rates is possible using
Timer 2.
Therefore, when Timer 2 is used to generate baud rates, the timer
increments every two clock cycles and not every core machine
cycle as before. Thus, it increments six times faster than Timer 1,
and therefore baud rates six times faster are possible. Because
Timer 2 has 16-bit autoreload capability, very low baud rates are
still possible.
Timer 2 is selected as the baud rate generator by setting the TCLK
and/or RCLK in T2CON. The baud rates for transmit and receive
can be simultaneously different. Setting RCLK and/or TCLK puts
Timer 2 into its baud rate generator mode as shown in Figure 53.
In this case, the baud rate is given by the formula:
Table XXV shows some commonly used baud rates and how they
might be calculated from a core clock frequency of 11.0592 MHz
and 12 MHz.
Ideal
Baud
19200 12
9600
2400
1200
19200 11.0592 –1 (FFH)
9600
2400
1200
Modes
TH2
(Core Clk)/(
Modes 1 and 3 Baud Rate =
Table XXV. Commonly Used Baud Rates, Timer 2
RELOAD
OVERFLOW
1
Core
CLK
(MHz)
12
12
12
11.0592 –1 (FFH)
11.0592 –1 (FFH)
11.0592 –2 (FFH)
TIMER 2
and
3
Baud Rate = ( /
32
RCAP2H
Value
–1 (FFH)
–1 (FFH)
–1 (FFH)
–2 (FEH)
1
1
× [
OVERFLOW
2
65536
TIMER 1
0
0
0
1
1 16
– RCAP H, RCAP L
RCAP2L
Value
–20 (ECH)
–41 (D7H)
–164 (5CH)
–72 (B8H)
–18 (EEH)
–36 (DCH) 9600
–144 (70H)
–32 (E0H)
RCLK
TCLK
(
16
16
) (Timer
SMOD
×
2
RX
CLOCK
TX
CLOCK
ADuC831
2
Actual %
Baud
19661
9591
2398
1199
19200
2400
1200
Overflow Rate)
2
)])
Error
2.4
0.1
0.1
0.1
0
0
0
0