Connectors
Table 2-3. 20-Pin ARM JTAG Header (continued)
Signal Name
Pin Number
Pin Number
Signal Name
TDO
13
14
GND
nRST
15
16
GND
NC
17
18
GND
NC
19
20
GND
2.2.2 Ethernet Interface
The RM57L843 integrates an MII/RMII Ethernet MAC on chip. This interface is routed to the on board
PHY via CBT switches. The board uses a DP83640 PHY. The interface is isolated and brought out to a
RJ-45 connector with integrated magnetics, J1. The pinmux control DIP S2 is used to control the CBT FET
switch for RMII, MII or other functions.
The J1 connector is used to provide a 10/100 Mbps Ethernet interface. This is a standard RJ-45
connector. The cable end pinout for the J1 connector is shown in
Table 2-4. J1, Ethernet Interface
Pin Number
Signal
Pin Number
Signal
1
D0+
2
D0-
3
D1-
4
D2+
5
D2-
6
D1-
7
D3+
8
D3-
Two LEDs are embedded into the connector to report link status (green LED) and transmit and receive
status of the PHY (yellow LED).
2.2.3 CAN Interface
The RM57L843 has up to three DCAN interfaces that provide a high-speed serial interface. Two 3-pin
screw terminal blocks, J2, J3, are used to interface to the DCAN bus. The pinouts for this connector are
shown in
. H means CAN High (CAN H), and L means CAN Low (CAN L).
CAN Bus termination is used to minimize signal reflection on the bus. ISO-11898 requires that the CAN
bus have a nominal characteristic line impedance of 120
Ω
. Therefore, the typical terminating resistor
value for each end of the bus is 120
Ω
. A split termination method is used to help increase EMC
performance. Split termination is a concept that is growing in popularity because emission reduction can
be achieved very easily. Split termination is a modified standard termination in which the single 120
Ω
resistor on each end of the bus is split into two 60
Ω
resistors, with a bypass capacitor tied between the
resistors and to ground. The two resistors should match as close as possible.
11
SPNU598 – May 2014
Physical Description
Copyright © 2014, Texas Instruments Incorporated
