TMS320F280041C: CRC calculation on the flash memory

Hi Alex,

This device does have enhancements to the C28x instruction set to greatly accelerate CRC calculation by the C28x CPU (VCU-CRC) but doesn't have a HW mechanism to compute CRC in the background independently of the CPU (other than using the CLA or CLA ROM CRC on devices that have CLA). 

The CLA ROM CRC does have a driverlib example in C2000ware in \ti\c2000\C2000Ware_<version>\driverlib\f28004x\examples\clapromcrc\

I don't think there is a VCU CRC example for F28004x, but the libraries and examples on some other devices can be found in \ti\c2000\C2000Ware_<version>\libraries\dsp\VCU\c28

There are libraries and examples for VCU0 and VCU2 only. TMS320F280041C has VCU1. Will VCU0 stuff work on VCU1? Can I use a flash address as a buffer pointer or I have to copy a block of flash memory to RAM first?

Alex

Hi Alex,

To be honest, I'm not sure how much modification, if any, is needed for the code to run on VCU-1 or if a flash address can be passed to the library.  Unfortunately, the primary and backup owners of VCU, who have more knowledge of the specific libraries, are all on vacation until Jan 3.  Can you wait until then for further clarification?     

Yes

Alex,

Is there any specific example under  libraries\dsp\VCU\c28\examples\crc that you want to be made working on VCU1 ?

Thanks

Aravindhan

Hi Aravindhan,

Actually I am not sure how to use the libraries TI provided. So, it would be much better if you could just write a C function to calculate CRC32 which can call assembler code if necessary.

uint32_t CalculateCRC32(uint32_t FlashStartAddr, uint32_t LengthIn32bitWords)

Please use the default values below:

 Default CRC generating polynomial
#define DEFAULT_CRC32_POLY  0x04C11DB7U  /*!< X^32 + X^26 + X^23 + X^22 + X^16 + X^12 + X^11 + X^10 +X^8 + X^7 + X^5 + X^4 + X^2+ X +1 */
Default CRC computation initialization value
#define DEFAULT_CRC_INITVALUE  0xFFFFFFFFU  /*!< Initial CRC default value */

If you can't do this I will work with our TI rep to make this function.

Alex

Alex, let me check and see if there is anything readily available. 

Alex,

Does the CRC  computation need to be done with performance in mind or not ? I am wondering if you can do this on the C28x without using the VCU if there is no need for optimized implementation.

Thanks

Aravindhan

Performance is important. I need to calculate flash CRC every powerup and possibly during operation. If VCU speeds up CRC calculation I want to use it. A function without utilizing VCU would work for now, during development, but I want to use VCU before the design goes in production.

Alex

Alex,

Okay. We need to then look at using VCU1. Do you have free bandwidth on C28x or that is fully utilized ? 

Thanks

Aravindhan

I have no clue about what you are asking. It is InstaSpin Lab7 with CAN J1939 protocols for communication. Just to be clear, F280041C has only one memory bank, if this is important, but there is still a lot of flash space available.

Alex,

I was asking if there is enough spare MHz on C28x CPU in the application you are trying to do. How big is the memory size on which we have to do the CRC computation ? 

Thanks

Aravindhan

I don't know the answer to your first question. The clock is at its max, 100 MHz. I have to assume I have spare MHz. 

Program Memory size is changing because of constant development. I am not sure why it matters. Start at 0x85000 and go to the end of the bank 0x8FFFF. Start address and the length should be parameters to the function.

Alex

Alex,

The size matters since computation time will depend on that. One of our teams probably has done a C28x based computation, I will check and revert back if there is one already done. 

Thanks

Aravindhan