Advertisement
Figure 7-10
Special Function Register ADCON (Address 0D8 H )
0DF H
0D8 H
BD
These bits are not used in controlling serial interface.
Bit
BD
Using timer 1 to generate baud rates:
Timer 1 can be used for generating baud rates in mode 1 and 3 of the serial channel. Then the baud
rate is determined by the timer 1 overflow rate and the value of SMOD as follows:
Mode 1, 3 baud rate =
The timer 1 interrupt is usually disabled in this application. The timer itself can be configured for
either "timer" or "counter" operation, and in any of its operating modes. In the most typical
applications, it is configured for "timer" operation in the auto-reload mode (high nibble of
TMOD = 0010B). In the case, the baud rate is given by the formula:
Mode 1, 3 baud rate =
One can achieve very low baud rates with timer 1 by leaving the timer 1 interrupt enabled,
configuring the timer to run as 16-bit timer (high nibble of TMOD = 0001B), and using the timer 1
interrupt for a 16-bit software reload.
Table 7-4 lists various commonly used baud rates and shows how they can be obtained from
timer 1.
Semiconductor Group
0DE H
0DD H 0DC H 0DB H
CLK
ADEX
BSY
Function
Baud rate enable.
When set, the baud rate in modes 1 and 3 of serial interface is taken from
a dedicated prescaler. Standard baud rates 4800 and 9600 baud at
12-MHz oscillator frequency can be achieved.
SMOD
2
x
(Timer 1 OV-rate)
32
SMOD
x oscillator frequency
2
32 x 12 x (256 – (TH1))
On-Chip Peripheral Components
0DA H
0D9 H
ADM
MX2
MX1
*
52
0D8 H
MX0
ADCON
Advertisement
