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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
Serial Data Link Module SDLM
User’s Manual
22-5
V2.2, 2004-01
SDLM_X, V2.0
22.2.1.2
J1850 Bits and Symbols
Figure 22-3
J1850 Variable Pulse Width (VPW) Format
Table 22-2
Timing Examples for VPW Format
Frequency
Tv1
Tv2
Tv3
Tv4
Tv5
Tv6
10.4 kbit/s
64
µ
s
128
µ
s
200
µ
s
280
µ
s
–
–
Passive
Active
Data Bit `1'
or
Passive
Active
Data Bit `0'
or
Start of Frame
Tv2
Tv1
Tv1
Tv2
(SOF)
Tv3
Passive
Active
End of Frame
(EOF)
Tv4
Passive
Active
Tv3
End of Data
(EOD)
Passive
Active
Normalization Bit
Tv3
Passive
Active
EOD
End of Last
Data Bit
Tv1 or Tv2
Norm. Bit
Start of
IFR Bit
Tv3
Passive
Active
EOD
End of Last
Data Bit
Idle bus, may initiate
transmission at any time
Inter-Frame
Separation
Tv4
Tv6
EOF
IFS
May transmit if rising
edge has been detected
after an EOF
> Tv3
End of Last
Data Bit
Tv6
EOF
IFS
Tv4
Break Signal
Passive
Active