p87c591vfb NXP Semiconductors, p87c591vfb Datasheet - Page 41

• Manufacturer Part Number: p87c591vfb
• Description: Single-chip 8-bit Microcontroller With Can Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
12.5.9
The contents of Bus Timing Register 1 defines the length of the bit period, the location of the sample point and the number
of samples to be taken at each bit time. This register can be accessed (read/write) if the Reset Mode is active. In
Operating Mode, this register is read only.
Table 20 Bus Timing Register 1 (BTR1) (CAN address 7)
12.5.9.1
Table 21 Sampling (SAM)
12.5.9.2
TSEG1 and TSEG2 determine the number of clock cycles per bit period and the location of the sample point:
2000 Jul 26
SAM
Single-chip 8-bit microcontroller with CAN controller
handbook, full pagewidth
SAM
BIT
7
CAN:
B
C:
US
Sampling (SAM)
Time Segment 1 (TSEG1) and Time Segment 2 (TSEG2)
T
1 (triple)
0 (once)
IMING
TSEG2.2
t SYNCSEG
sync.
seg.
t scl
6
R
VALUE
EGISTER
t TSEG1
TSEG2.1
1 (BTR1)
t CLK
t TSEG1
TSEG1
t TSEG2
=
nominal bit time
5
t scl
The bus is sampled three times
-> recommended for low/medium speed buses (class A and B) where filtering
The bus is sampled once
-> recommended for high speed buses (SAE class C)
sample point(s)
Fig.12 General structure of a bit period.
=
8 TSEG1.3
spikes on the bus-line is beneficial
t scl
TSEG2.0
baud rate prescaler
t SYNCSEG
4
4 TSEG2.2
+
t TSEG2
TSEG2
4 TSEG1.2
41
TSEG1.3
=
+
1 t scl
2 TSEG2.1
3
sync.
seg.
+
2 TSEG1.1
FUNCTION
+
TSEG1.2
TSEG2.0
e.g.
2
+
TSEG1
TSEG1.0
BRP = 000010b
TSEG1 = 0101b
TSEG2 = 010b
+
1
TSEG1.1
+
1
Preliminary Specification
1
P8xC591
MHI011
TSEG1.0.
0