S12 / MagniV MicrocontrollersのトピックRe: Abraham Test for internal SRAM - block size

Abraham Test for internal SRAM - block size

kam2630 — Mon, 09 Mar 2015 19:57:37 GMT

Hello embedded world,

We are working on an Abraham Ram Test for the internal SRAM of the S12XDP512 µC.

Now the questions arrives how to choose the correct block size to split the test into several partitions.

Is there any description of the RAM structure available or better can anyone give us a hint for the block size ?

Thanks a lot

Karl

lama — Thu, 12 Mar 2015 08:06:16 GMT

Hi,

I am waiting for answer from a design team. As soon as I have it i'll share it.

Best regards,

Ladislav

kam2630 — Wed, 25 Mar 2015 10:46:12 GMT

Dear Ladislav,

Might it be possible to escalate this item, we are still standby waiting for help.

Many thanks for your efforts,

Karl

iggi — Fri, 27 Mar 2015 11:22:57 GMT

Hi Karl,

Well, the RAM consists of one 32K block on the S12XDP512 device.

You can access directly 4K RAM at address 0x1000 - 0x2000 and 8K RAM part from 0x2000-0x4000. However this is only 12Kbytes.

Entire 32K RAM can be accessed through pages. There is 4K RAM window at local address 0x1000 - 0x2000 and 8 RAM pages 0xF8 to 0xFF.

On the other hand there is global memory map and 32K RAM starts at address 0xF_8000 and ends at 0xF_FFFF.

NOTE:

In the S12 architecture, the biggest size that an object can have is 16kB. This limitation is imposed by the

CPU local map, where the biggest continuous memory space accessible at a time by the CPU is 16kB. In

the S12 architecture attempting to allocate an object bigger than 16kB results in a linker error.

To reduce this limitation, in the S12X architecture, another method for accessing memory has been

introduced: Global addressing.

Hopefully the information above can be of help.

regards,

iggi