JTAG : Debuggin the memory-mapped OCTOSPI RAM or FLASH

[BRado]

Hello,

It'is possible to configure Debugger to access to an external memory-mapped Memory (OCTOSPI) ?

Thanks

[Andreas Bolsch]

Depends on the meaning of "debugger accesses". When it's memory mapped (and MPU doesn't interfere), it's mapped into the CPU's memory space like an internal memory, so the debugger has full *READ* access. However, write access is a different matter, so e.g. software breakpoints don't work in a straightforward way ...

[BRado]

Exactly, can you explain the way to allow the write access to debugger ?

Thank's

[Andreas Bolsch]

That's totally unrelated to a debugger. The OctoSPI and the external memory have to be set up properly to be accessible by the CPU in memory mapped mode, then it is accessible by a debugger, too.

In general for NOR flash: not possible, as write means: 1) erase affected (sub-) sector, 2) write. And both operations need setting the write enable by an extra command, and after erase/write polling for end of operation. For SPI-RAM (these are rather exotic) one would configure the RAM for sequential addressing mode first, then set up the write CCR, write instruction, ... registers in same fashion as the read counterparts. Then the memory-mapped mode would work for read and write in the same way (albeit much slower) as for internal RAM.