uint8_t buffer size definition

Alessandro Petrizzi

Other Parts Discussed in Thread: MSP430F5659

Hi,

I'm working with MSP430F5659 on TS430Pz100USB and I need to create a uint8_t buffer[50000]. But when I try building my project I obtain error: "size of array ‘buffer’ is too large".

My buffer can reach only 10000 elements dimensions.

Is it possible to create and use array larger than that size? I see in data-sheet that MSP430F5659 has 512 KB Flash and 64 KB SRAM.

How can I obtain my target of 50000 size buffer?

I use CCS v. 6.0.0.00190 and GNU compiler v. 4.8.0 (Red Hat)

Thanks in advance for your answers and advices.

over 9 years ago

0 Leo Hendrawan over 9 years ago

TI__Guru 56650 points

Hi,

the MSPGCC delivered in CCS 6.0 is still in BETA version. Please use the CCS compiler (v4.3.1 with CCS v6.0) or wait until the newer version is released.

0 Leo Hendrawan over 9 years ago in reply to Leo Hendrawan

TI__Guru 56650 points

Hi,

I also found out that this is due to hardware limitation. The64 KB SRAM is divided into 2 segments:

RAM : origin = 0x2400, length = 0x4000
RAM2 : origin = 0xF0000, length = 0xC000

Therefore a continuous SRAM is 48KB from 0xF0000 to 0xFBFFF. Using CCS Compiler CGT v4.3.1 I can have data buffer up to 40000.

0 Alessandro Petrizzi over 9 years ago in reply to Leo Hendrawan

Prodigy 75 points

Thank you Leo,

I'll try with your suggestions.

In the meantime I found another recent useful discussion to solve my problem:

http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/339514.aspx?pi307167=1

Thanks,
Alessandro

0 Jens-Michael Gross over 9 years ago in reply to Leo Hendrawan

Guru 227245 points

There’s another limitation: AFAIK, the array index usually is a signed int, so its maximum value is 32767. I’m not sure whether an array can be larger than 32768 elements at all.

Well, if this is a compiler limitation, it might be tricked by defining an uint16_t array with 25000 members and then assign its pointer into an uint8_t pointer:

uint16_t buf[25000];
uint8_t * const buffer = (uint8_t*)buf;
and then access the data with
uint8_t data = *(buffer+index); // this is not exactly the same as buffer[index]

Well, that’s just an idea. :)

0 Alessandro Petrizzi over 9 years ago in reply to Jens-Michael Gross

Prodigy 75 points

Hi Jens-Michael,

I'm still working on the project with uint8_t very large array, but I have overcome the problem exposed, with the interesting discussion that I had stated:

http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/339514.aspx?pi307167=1

Anyway, thanks for your useful trick that I could use the next time. I really enjoyed.

Regards,
Alessandro

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uint8_t buffer size definition