EP80579 Datasheet, PDF (1580/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
Table 39-2. CAN Recommended Bit Rate and Timing Parameters
Bit Rate
(Kbs/s)
Nominal
Bit Time
(us)
Number
of Time
Quanta
Per Bit
Nominal
Bit Time /
CAN
Controller
Frequency
†
Time
Quantum
(us)
Bit Rate
Scaler
Required
for
40Mhz
CAN
Clock
1000
1
8
40
0.125
5
800
1.25
10
50
0.125
5
500
2
16
80
0.125
5
250
4
16
160
0.250
10
125
8
16
320
0.500
20
50
20
16
800
1.250
50
20
50
16
2000
3.125
125
10
100
16
4000
6.250
250
The bit rate scaler is chosen such that this is an integer value.
CAN Clock Frequency = 40Mhz
cfg_tseg2 = 1
cfg_sjw = 0
Single Sampling Mode
Synchronization Mode: Recessive to dominant only
cfg_tseg1
(Tseg - 1)
4
6
12
12
12
12
12
12
cfg_bitrate
4
4
4
9
19
49
124
249
39.5
39.5.1
39.5.2
Theory of Operation
Modes of Operation
The CAN unit can be used in different operating modes. By disabling transmitting data,
it is possible to use the CAN in listen-only mode, enabling features such as automatic
bit rate detection. The two units can be used in an on-chip loop-back mode.
Before starting the CAN controller, all CAN configuration registers must be set
according to the target application.
Error Handling
The CAN protocol provides sophisticated error detection mechanisms. The following list
of errors can be detected:
• Cyclic Redundancy Check (CRC) Error - The received CRC sequence did not match
the calculated result.
• Acknowledge Error - The transmitter did not detect a dominant bit during ACK slot.
• Form Error - One or more illegal bits in a fixed-form bit field.
• Bit Error - The monitored bit value is different from the bit value sent.
• Stuff Error - Between Start of Frame and CRC Delimiter, 6 consecutive bits with the
same polarity are detected.
An interrupt will be generated if an error is enabled and detected, see “Offset
00000000h: Int_status - Interrupt Status Register”.
Intel^® EP80579 Integrated Processor Product Line Datasheet
1580
August 2009
Order Number: 320066-003US