PIC16C65A Microchip Technology, PIC16C65A Datasheet - Page 110

• Manufacturer Part Number: PIC16C65A
• Description: 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

PIC16C6X
12.1.1
The data on the RC7/RX/DT pin is sampled three times
by a majority detect circuit to determine if a high or a
low level is present at the RX pin. If bit BRGH
(TXSTA<2>) is clear (i.e., at the low baud rates), the
sampling is done on the seventh, eighth and ninth fall-
ing edges of a x16 clock (Figure 12-3). If bit BRGH is
FIGURE 12-3: RX PIN SAMPLING SCHEME (BRGH = 0) PIC16C63/R63/65/65A/R65)
FIGURE 12-4: RX PIN SAMPLING SCHEME (BRGH = 1) (PIC16C63/R63/65/65A/R65)
FIGURE 12-5: RX PIN SAMPLING SCHEME (BRGH = 1) (PIC16C63/R63/65/65A/R65)
DS30234D-page 110
RC7/RX/DT pin
Q2, Q4 clk
(RC7/RX/DT pin)
baud clk
x4 clk
SAMPLING
baud CLK
x16 CLK
RC7/RX/DT pin
RX
Q2, Q4 clk
baud clk
x4 clk
1
2
First falling edge after RX pin goes low
3
1
4
1
Start Bit
Samples
First falling edge after RX pin goes low
5
2
6
Second rising edge
3
Samples
7
Samples
4
Start Bit
8
2
1
Samples
set (i.e., at the high baud rates), the sampling is done
on the 3 clock edges preceding the second rising edge
after the first falling edge of a x4 clock (Figure 12-4 and
Figure 12-5).
Second rising edge
9
Start bit
bit0
10
Baud clk for all but start bit
2
11
3
Baud CLK for all but start bit
12
4
3
13
1
Samples
14
bit1
1997 Microchip Technology Inc.
2
15
16
1
4
2
Bit0
3
bit0