MPC555
/
MPC556
CAN 2.0B CONTROLLER MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
16-28
16.7.5 Control Register 1
Table 16-14 RX MODE[1:0] Configuration
Pin
RX1
RX0
Receive Pin Configuration
CNRX1
1
NOTES:
1. The CNRX1 signal is not available on the MPC555
/
MPC556.
0
X
A logic zero on the CNRX1 pin is interpreted as a dominant bit; a logic one on the
CNRX1 pin is interpreted as a recessive bit
1
X
A logic one on the CNRX1 pin is interpreted as a dominant bit; a logic zero on the
CNRX1 pin is interpreted as a recessive bit
CNRX0
X
0
A logic zero on the CNRX0 pin is interpreted as a dominant bit; a logic one on the
CNRX0 pin is interpreted as a recessive bit
X
1
A logic one on the CNRX0 pin is interpreted as a dominant bit; a logic zeroon the
CNRX0 pin is interpreted as a recessive bit
Table 16-15 Transmit Pin Configuration
TXMODE[1:0]
Transmit Pin Configuration
00
Full CMOS
1
; positive polarity (CNTX0 = 0, CNTX1
= 1 is a dominant level)
2
NOTES:
1. Full CMOS drive indicates that both dominant and recessive levels are driven by the chip.
2. The CNTX1 signal is not available on the MPC555
/ MPC556.
01
Full CMOS; negative polarity (CNTX0 = 1, CNTX1
= 0 is a dominant level)
1X
Open drain
3
; positive polarity
3. Open drain drive indicates that only a dominant level is driven by the chip. During a reces-
sive level, the CNTX0 and CNTX1 pins are disabled (three stated), and the electrical level
is achieved by external pull-up/pull-down devices. The assertion of both Tx mode bits caus-
es the polarity inversion to be cancelled (open drain mode forces the polarity to be positive).
CANCTRL1 —
Control Register 1
0x30 7086
0x30 7486
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
CANCTRL0
SAMP
Re-
served
TSYNC LBUF
0D
PROPSE
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
.
..