AP29000
Connecting C166 and C500 Microcontroller to CAN
Examples for the Connection of Infineon Microcontrollers to CAN
Application Note 39 V 1.0, 2004-02
Every access to the SAE 81C91 is started by activating the device (CS# = 0),
performed by a port pin (e.g. P1.6). Pin P1.5 of the C511 / C513 then selects a read
(W# = 1) or a write (W# = 0) operation via the W# input of the CAN controller. Then the
address of the register to be read or written is sent to the SAE 81C91 via the line
connecting pin STO (SSC Transmit Output) with pin DI (Data Input). Depending on the
operation, one or more (if the automatic decrementing of the address is activated in
the CAN controller by setting bit ADE in the MOD register) data bytes can be written to
the SAE 81C91 or can be read via the line between pin SRI (SSC Receive Input) and
pin DO (Data Output). Finally, the CAN controller has to be deactivated again
(CS# = 1).
The synchronization of the controllers is done via the line SCLK - CLK. Data from pin
DI are always transferred into the internal shift register with the rising edge of the
clock. The level applied to the timing pin (TIM) of the CAN controller decides whether
data is output at the DO pin with the rising edge (TIM = 0) or with the falling edge
(TIM = 1, see figure 4.3-1) of the CLK signal. Pin P1.7 of the C511 / C513 controls the
slope control pin of the CAN transceiver, when available. On the CAN controller side,
an inactive level is applied to pins WR#, RD#, and ALE, and to pins AD5 to AD7, which
are not required when the serial connection between the SAE 81C91 and the host
controller is used.
5.4 A proposal for the CAN Bus Cables
The CAN standard does not include the connectors with which an application is
connected to the bus lines. A proposal of the CAN user group "CAN in Automation"
(CiA) uses 9-pole SUB-D connectors with the following pin usage:
Table 1
Pin Signal Description
1 — (reserved)
2 CAN_L CAN_L bus line
3 GND ground
4 — (reserved)
5 — (reserved)
6 (GND) optional ground
7 CAN_H CAN_H bus line
8 — (reserved)
9 (V+) opt. power supply
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