SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
To enable write access to register TEST (see Section 2.3.5), bit CCCR.TEST has to be set to one. This allows the configuration of the test modes and test functions.
Four output functions are available for the CAN transmit pin m_can_tx by programming TEST.TX. Additionally to its default function – the serial data output – it can drive the CAN Sample Point signal to monitor the M_CAN’s bit timing and it can drive constant dominant or recessive values. The actual value at pin m_can_rx can be read from TEST.RX. Both functions can be used to check the CAN bus’ physical layer.
Due to the synchronization mechanism between CAN clock and Host clock domain, there may be a delay of several Host clock periods between writing to TEST.TX until the new configuration is visible at output pin m_can_tx. This applies also when reading input pin m_can_rx via TEST.RX.
Test modes should be used for production tests or self test only. The software control for pin m_can_tx interferes with all CAN protocol functions. It is not recommended to use test modes for application.