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| 型号： | MCP2510-E/SOG |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 1 CHANNEL(S), 1M bps, LOCAL AREA NETWORK CONTROLLER, PDSO18 |
| 封装： | 0.300 INCH, PLASTIC, SOIC-18 |
| 文件页数： | 31/80页 |
| 文件大小： | 998K |
| 代理商： | MCP2510-E/SOG |
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2007 Microchip Technology Inc.
DS21291F-page 37
MCP2510
5.7
Synchronization
To compensate for phase shifts between the oscillator
frequencies of each of the nodes on the bus, each CAN
controller must be able to synchronize to the relevant
signal edge of the incoming signal. Synchronization is
the process by which the DPLL function is imple-
mented. When an edge in the transmitted data is
detected, the logic will compare the location of the edge
to the expected time (Sync Seg). The circuit will then
adjust the values of phase segment 1 and phase seg-
ment 2 as necessary. There are two mechanisms used
for synchronization.
5.7.1
HARD SYNCHRONIZATION
Hard Synchronization is only done when there is a
recessive to dominant edge during a BUS IDLE condi-
tion, indicating the start of a message. After hard syn-
chronization, the bit time counters are restarted with
Sync Seg. Hard synchronization forces the edge which
has occurred to lie within the synchronization segment
of the restarted bit time. Due to the rules of synchroni-
zation, if a hard synchronization occurs there will not be
a resynchronization within that bit time.
5.7.2
RESYNCHRONIZATION
As a result of Resynchronization, phase segment 1
may be lengthened or phase segment 2 may be short-
ened. The amount of lengthening or shortening of the
phase buffer segments has an upper bound given by
the Synchronization Jump Width (SJW). The value of
the SJW will be added to phase segment 1 (see
Figure 5-2) or subtracted from phase segment 2 (see
Figure 5-3). The SJW represents the loop filtering of
the DPLL. The SJW is programmable between 1 TQ
and 4 TQ.
Clocking information will only be derived from reces-
sive to dominant transitions. The property that only a
fixed maximum number of successive bits have the
same value ensures resynchronization to the bit stream
during a frame.
The phase error of an edge is given by the position of
the edge relative to Sync Seg, measured in TQ. The
phase error is defined in magnitude of TQ as follows:
e = 0 if the edge lies within SYNCESEG
e > 0 if the edge lies before the SAMPLE POINT
e < 0 if the edge lies after the SAMPLE POINT of
the previous bit
If the magnitude of the phase error is less than or equal
to the programmed value of the synchronization jump
width, the effect of a resynchronization is the same as
that of a hard synchronization.
If the magnitude of the phase error is larger than the
synchronization jump width, and if the phase error is
positive, then phase segment 1 is lengthened by an
amount equal to the synchronization jump width.
If the magnitude of the phase error is larger than the
resynchronization jump width, and if the phase error is
negative, then phase segment 2 is shortened by an
amount equal to the synchronization jump width.
5.7.3
SYNCHRONIZATION RULES
Only one synchronization within one bit time is
allowed
An edge will be used for synchronization only if
the value detected at the previous sample point
(previously read bus value) differs from the bus
value immediately after the edge
All other recessive to dominant edges fulfilling
rules 1 and 2 will be used for resynchronization
with the exception that a node transmitting a dom-
inant bit will not perform a resynchronization as a
result of a recessive to dominant edge with a pos-
itive phase error
FIGURE 5-2:
LENGTHENING A BIT PERIOD
Input Signal
Sync
Prop
Segment
Phase
Segment 1
Phase
Segment 2
≤ SJW
Sample
Nominal
Actual Bit
Length
Bit Length
Point
TQ
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相关代理商/技术参数 |
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|---|---|
| MCP2510-EST | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Stand-Alone CAN Controller with SPI Interface |
| MCP2510-I/P | 功能描述:网络控制器与处理器 IC Stand-alone CAN RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| MCP2510-I/P | 制造商:Microchip Technology Inc 功能描述:IC CAN CONTROLLER 2510 DIP18 |
| MCP2510-I/SO | 功能描述:网络控制器与处理器 IC Stand-alone CAN RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| MCP2510-I/SO | 制造商:Microchip Technology Inc 功能描述:IC CAN CONTROLLER 2510 SOIC18 |
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