𝑺𝒐𝒇𝒕𝒘𝒂𝒓𝒆 𝑶𝒗𝒆𝒓 𝑻𝒉𝒆 𝑨𝒊𝒓 (𝑺𝑶𝑻𝑨) 

𝑺𝒐𝒇𝒕𝒘𝒂𝒓𝒆 𝑶𝒗𝒆𝒓 𝑻𝒉𝒆 𝑨𝒊𝒓 (𝑺𝑶𝑻𝑨) is a modern technique that facilitates remote software updates for devices. The AURIX TC3xx microcontrollers have implemented this feature to allow seamless software updates, with the exception of the TC33x and TC33xED models.

The functionality of SOTA for Aurix TC3xx series is as follows:

𝑫𝒖𝒂𝒍 𝑷𝑭𝑳𝑨𝑺𝑯 𝑩𝒂𝒏𝒌𝒔:

The TC3xx microcontrollers enhance SOTA by dividing the PFLASH into two distinct groups of banks, termed as Group A and Group B. This bifurcation allows one group to be actively read and executed from, while the other group can be written with new code. It’s a strategic design since within a single physical PFLASH bank, simultaneous read-while-write (RWW) isn’t supported. The dual-bank system ensures that SOTA updates are executed securely and reliably.

𝑨𝒄𝒕𝒊𝒗𝒆 𝒂𝒏𝒅 𝑰𝒏𝒂𝒄𝒕𝒊𝒗𝒆 𝑩𝒂𝒏𝒌𝒔:

When SOTA is operational, one set of PFLASH banks is mapped to CPU executable address space and is designated as the ‘active’ banks.
Conversely, the other set is labeled as the ‘inactive’ banks, which are mapped to a set of addresses that allow them to be read from and written to.
Post a SOTA update, a swap occurs, but only in terms of address mapping, ensuring that the address range executed from remains unchanged, and no data copying is required.

𝑨𝒅𝒅𝒓𝒆𝒔𝒔 𝑴𝒂𝒑𝒑𝒊𝒏𝒈:

The physical address of the PFLASH banks adheres to the standard address map as discussed in the “Address Map” chapter. When a SOTA address map switch takes place, the reading and code execution mapping of the PFLASH banks are detailed in the alternate address map, also available in the Address Map chapter. Within this context, the active group in the standard address map is denoted as ‘A’, while the active group in the alternate address map is labeled as ‘B’.

𝑵𝒐𝒏-𝑽𝒐𝒍𝒂𝒕𝒊𝒍𝒆 𝑴𝒆𝒎𝒐𝒓𝒚 𝑶𝒑𝒆𝒓𝒂𝒕𝒊𝒐𝒏𝒔:

All operations on NVM are executed via the DMU using the physical system address of the PFLASH. This means that any NVM operation always resorts to the standard address map, irrespective of the swap settings. Here, the term ‘NVM operation’ indicates any command sequence, such as programming or erasing, targeting a FLASH and excludes reads.

𝑪𝒐𝒏𝒇𝒊𝒈𝒖𝒓𝒂𝒕𝒊𝒐𝒏 𝒂𝒏𝒅 𝑺𝒂𝒇𝒆𝒕𝒚:

Parameters that control the SOTA address map switching and associated functions are preset in the User Configuration Block (UCB).
Post configuration, the hardware settings are updated by the on-chip system firmware only during the subsequent System Reset. This design choice is deliberate to prevent any unintentional modifications during application execution.

(The flow chart illustrates the Runtime SOTA configuration in TC3xx devices)

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An Article by: Yashwanth Naidu Tikkisetty
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