topic SRAM problem MPC5775K in MPC5xxx

SRAM problem MPC5775K

whoam — Mon, 13 Nov 2017 12:34:42 GMT

Hi,

I have a question about SRAM. I attached a part of the SRAM when viewed with Lauterbach. Some addresses can't be read. When I want to write to one address with parameter long, there is an bus error, but when i write with Lauterbach a quad value, the writing works and I can see the data afterwards. Do you know why there are bus errors at all and why the writing works with parameter quad?

So for example this command works: Data.Set EA:0x40000000 %Quad 0

but this one is not working: Data.Set EA:0x40000000 %Long 0

I want to use the SSD Driver, so i must be able to write to RAM.

Thanks in advance

whoam

Re: SRAM problem MPC5775K

davidtosenovjan — Mon, 13 Nov 2017 16:50:57 GMT

Hi, you probably see uninitialized SRAM. SRAM initialization must be included in the MCU startup code.

Reset state of internal SRAM is random, thus data and checkbits may contain any data. Most probably the first read attempt to any address would generate non-correctable ECC error. SRAM must be initialized after power-up. Typically it means the whole SRAM is deleted or written by any value, however it must be either 64-bit write to completely define ECC code for data unit.

Re: SRAM problem MPC5775K

whoam — Wed, 15 Nov 2017 08:06:36 GMT

Thanks David, i think the initialization was the problem!

I still have one more question. Do you know how i can check the RAM/Memory values with Lauterbach when I'm writing them with my external tool (so I can check if the SSD/SSD Config writing was correct)? When I'm using both tools parallel Lauterbach is showing 'debug port fail' error and when I'm powering of my external tool Lauterbach is shwoing 'target reset' in Data Dump and I need to reset the MPC5775K first to see the vaules, but this reset of course deletes the values in SRAM. DO you know how i can manage to check my data writes with Lauterbach?

Thank you,

whoam