C501G-1E SIEMENS [Siemens Semiconductor Group], C501G-1E Datasheet - Page 67

• Manufacturer Part Number: C501G-1E
• Description: 8-Bit Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

6.3.3.1
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” operation, and in any of its 3 running modes. In the most typical
applications, it is configured for “timer” operation, in the auto-reload mode (high nibble of
TMOD=0010B). In that case, the baud rate is given by the formula
One can achieve very low baud rates with timer 1 by leaving the timer 1 interrupt enabled, and
configuring the timer to run as a 16-bit timer (high nibble of TMOD = 0001 B ), and using the timer 1
interrupt to do a 16-bit software reload.
Table 6-7 lists commonly used baud rates and how they can be obtained from timer 1.
Table 6-7
Timer 1 Generated Commonly Used Baud Rates
Baud Rate
Mode 0 max: 1 MHz
Mode 2 max: 375 K
Modes 1, 3: 62.5 K
19.2 K
9.6 K
4.8 K
2.4 K
1.2 K
110
110
Semiconductor Group
Modes 1,3 baud rate = 2
Modes 1,3 baud rate = 2
Using Timer 1 to Generate Baud Rates
SMOD
SMOD
/32 (timer 1 overflow rate)
/32
f
OSC
f
12 MHz
12 MHz
12 MHz
11.059 MHz
11.059 MHz
11.059 MHz
11.059 MHz
11.059 MHz
6 MHz
12 MHz
OSC
/ [12 (256–TH1)]
6-33
SMOD
X
1
1
1
0
0
0
0
0
0
On-Chip Peripheral Components
C/T
X
X
0
0
0
0
0
0
0
0
Mode
X
X
2
2
2
2
2
2
2
1
Timer 1
Reload
Value
X
X
FF H
FD H
FD H
FA H
F4 H
E8 H
72 H
FEEB H
C501