This article describes device specifics of the Infineon XMC4500 microcontroller.
Flash sector limitations
The Infineon XMC4500 device series comes with the following physical sector layout:
- 2 * 64 kB
- 1 * 128 kB
- x * 256 kB
The first 64 KB physical sector consists of four logical 16 KB sectors which can be accessed (erased) individually. Therefore instead of erasing the whole 64 KB physical sector, the first physical sector can be erased 16 KB wise and therefore, e.g. used to have a bootloader which does not change in the first 16 KB logical sector while having the application starting in the second logical sector (offset 16 KB). This way, the application can be exchanged without erasing the bootloader.
However, the J-Link software uses the physical sector layout for two reasons:
- Writing into logical flash sectors disturbs adjacent data in the remaining logical sectors and thus increasing the risk of having incorrect data stored in the remaining memory sectors
- Decrease of total flash erase cycles possible as a logical sector access promotes uneven memory degradation
For further information regarding this, please refer to the technical reference manual of the Infineon XMC4500 series.
However, under special circumstances customers may want to use the logical sector layout. For such scenarios, the J-Link DLL allows to perform a read-modify-write to a flash sector in order to *not* erase certain parts of the physical sector when programming / erasing logical sectors.
Further information regarding this as well as an example can be found here: Link
Attach to running application
For the Infineon XMC4xxx series devices it is not supported to attach to a running target. J-Link needs to perform a reset during the connect phase, to guarantee a stable debug connection and session. This behavior was requested by Infineon when support for the XMC4xxx series was implemented by SEGGER. Without a reset being performed at start of the debug connection, unexpected behavior of target applications have been seen because the MCU seemed to not behave correctly from the debug side.
The XMC 4xxx-series requires a specific connect sequence in which the JTAG chain is configured. By default, the XMC4xxx device is expected to be at the first position of the chain with one different, unknown device behind it. Therefore, when using a different setup, the JTAG chain has to be configured manually since there is no way to auto-detect the position reliably. In such cases, please get in touch with SEGGER directly (firstname.lastname@example.org).