eCAN Configuration
www.ti.com
800
SPRUI07–March 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
Controller Area Network (CAN)
13.7.5.2 Precautions for Entering and Exiting Device Low-Power Modes (LPM)
The 28x device features two low-power modes, STANDBY and HALT, in which the peripheral clocks are
turned off. Since the CAN module is connected to multiple nodes across a network, you must take care
before entering and exiting device low-power modes such as STANDBY and HALT. A CAN packet must
be received in full by all the nodes; therefore, if transmission is aborted half-way through the process, the
aborted packet would violate the CAN protocol resulting in all the nodes generating error frames. The
node exiting LPM should do so unobtrusively. For example, if a node exits LPM when there is traffic on
the CAN bus it could “see” a truncated packet and disturb the bus with error frames.
The following points must be considered before entering a device low-power mode:
1. The CAN module has completed the transmission of the last packet requested.
2. The CAN module has signaled to the CPU that it is ready to enter LPM.
In other words, device low-power modes should be entered into only after putting the CAN module in local
power-down mode.
13.7.5.3 Enabling or Disabling Clock to the CAN Module
The CAN module cannot be used unless the clock to the module is enabled. It is enabled or disabled by
using bit 14 of the PCLKCR0 register for eCAN-A module and bit 15 of PCLKCR0 register for eCAN-B
module. This bit is useful in applications that do not use the CAN module at all. In such applications, the
CAN module clock can be permanently turned off, resulting in some power saving. This bit is not intended
to put the CAN module in low-power mode and should not be used for that purpose. Like all other
peripherals, clock to the CAN module is disabled upon reset.
13.7.5.4 Possible Failure Modes External to the CAN Controller Module
This section lists some potential failure modes in a CAN based system. The failure modes listed are
external to the CAN controller and hence, need to be evaluated at the system level.
• CAN_H and CAN_ L shorted together
• CAN_H and/or CAN_ L shorted to ground
• CAN_H and/or CAN_ L shorted to supply
• Failed CAN transceiver
• Electrical disturbance on CAN bus
To Next Page
Loading...
Need help?
General
