The IM-AD1 has two CAN interfaces provided by Bosch CC770 serial communications controllers. The network interfaces are provided by Philips TJA1050 transceivers, each capable of 1Mb/s data transfer.
Figure 3.8 shows the architecture of the CAN interface. The CAN controllers are 5V devices and are supported by buffers at their interface with the 3.3V system buses provided by the logic module. The CAN controllers are configured to operate with an 8-bit non-multiplexed asynchronous host interface. Each of the CAN controllers has a 16MHz crystal that it uses for its internal clocks.
All interface signals are routed to the logic module. The CAN controllers are supported by an AHB interface instantiated into the logic module code example supplied with the IM-AD1.
The transmit and receive data signals, CANx_TXD and CANx_RXD, at the EXPIM connectors are not used for the normal operation of the interfaces. They are provided to allow you to implement your own CAN controller logic in the logic module FPGA.
The surface mount links, LK1 and LK2, are provided so that the transmit data signals to the TJA1050 transceivers can be driven either from the CAN controllers or directly from the logic module FPGA.
Table 3.8 shows the assignment of the CAN controller interface signals to the logic module signals on the EXPIM connector.
|CAN_A[7:0]||IM_BBANK[7:0]||CAN address bus|
|CAN_D[7:0]||IM_BBANK[8:15]||CAN data bus|
|CAN_T/R||IM_BBANK16||CAN buffer direction control|
|CAN_nOE||IM_BBANK17||CAN buffer output enable|
|CAN1_nRESET||IM_BBANK18||CAN1 reset signal|
|CAN2_nRESET||IM_BBANK19||CAN2 reset signal|
|CAN_R/nW||IM_BBANK20||CAN read / write|
|CAN1_nCS||IM_BBANK21||CAN1 chip select|
|CAN2_nCS||IM_BBANK22||CAN2 chip select|
|CAN1_TXD||IM_BBANK23||CAN1 transmit data|
|CAN2_TXD||IM_BBANK24||CAN2 transmit data|
|CAN1_nDSACK0||IM_BBANK25||CAN1 data acknowledge|
|CAN2_nDSACK0||IM_BBANK26||CAN2 data acknowledge|
|CAN1_RXD||IM_BBANK29||CAN1 receive data|
|CAN2_RXD||IM_BBANK30||CAN2 receive data|
You connect the CAN interfaces through the 9-pin D-type plugs J3A (top) and J3B (bottom), with CAN1 connecting to J3A.
Figure 3.9 shows the pin locations for this type of connector.
Table 3.9 shows the signal assignment.