T89C51CC02 Atmel, T89C51CC02 Datasheet - Page 74

• Manufacturer Part Number: T89C51CC02
• Description: 8-Bit MCU
• Manufacturer: Atmel

T89C51CC02
15.5. Bit Timing and BaudRate
The baud rate selection is made by Tbit calculation:
Tbit = Tsyns + Tprs + Tphs1 + Tphs2
1. Tsyns = Tscl = (BRP[5..0]+ 1) / Fcan.
2. Tprs = (1 to 8) * Tscl = (PRS[2..0]+ 1) * Tscl
3. Tphs1 = (1 to 8) * Tscl = (PHS1[2..0]+ 1) * Tscl
4. Tphs2 = (1 to 8) * Tscl = (PHS2[2..0]+ 1) * Tscl
5. Tsjw = (1 to 4) * Tscl = (SJW[1..0]+ 1) * Tscl
The total number of Tscl (Time Quanta) in a bit time is from 8 to 25.
example:
For a Baud Rate of 100 kbit/s and Fosc = 12 MHz For have 10 TQ:
BRP = 5
PRS = 2
PHS2 = 2
PHS1 = 2
74
(1)
(2)
(3)
(4)
Phase error 0
Phase error 0
Phase error > 0
Phase error < 0
system clock
oscillator
data
Tsyns
(*)
Figure 60. General structure of a bit period
Synchronization Segment: SYNS
1/ Fcan
(*)
Tsyns = 1xTscl (fixed)
Tscl
Preliminary
Tbit calculation:
Tprs
one nominal bit
Bit Rate Prescaler
Tbit
Tbit
Tphs1 + Tsjw
=
Tphs1
Tsyns
(1)
Sample Point
(3)
+
Tprs
Tphs2 - Tsjw
+
Tphs1
Tphs2
Rev.A - May 17, 2001
Transmission Point
(2)
+
Tphs2
(4)