RTT

Modes

SEGGER RTT (SEGGER Real Time Transfer) can run in different modes where some modes are not available on all devices but other modes are which then have an impact on the real time behavior of the device.

Background mode

This is the mode which RTT was initially introduced with. In this mode, J-Link can access the memory of the target system while the MCU + application keeps running (background memory access), effectively not impacting the real time behavior of the application. In order to use this mode, the target MCU needs to support background memory accesses.

The following devices support background memory accesses:

• Cortex-M based devices (all cores from the series)
• Renesas RX based devices (all cores from the series)

The following cores can optionally support background memory accesses:

• Cortex-A based devices (all cores from the series)
• Cortex-R based devices (all cores from the series)

For Cortex-A/R it depends on the actual device if it supports background memory accesses because it is up to the device vendor if the necessary hardware unit is implemented or not. In addition to that, when using the background mode on Cortex-A/R based devices, some considerations need to be taken into account when it comes to caches etc. These are explained in AN08005

Stop mode

TBD