RTOS/AM3358: Profibus Master and Ethernet

JHi,

>>Why doesn't profibus master work when cache is enabled?

You may refer to the reference design - Industrial Communications Gateway PROFINET® IRT to PROFIBUS® Reference Design ().

PROFIBUS requires 1MB memory DDR region to be uncached for PRU driver memory mapping. The DDR memory cache-ability is configured in .cfg file, where several memory sections with various cache-ability attributes will be defined. So you can enable the cache but keep the 1MB for PROFIBUS in un-cached section, e.g. update the starting address from default 0x8200_0000 to 0x9200_0000 as below in SwPruss.c.

int PRUSSDRVMapExtMem(void **address)
{
*address = (void *)0x92000000;
return 0;

}

The following is the code snippet for uncached DDR memory region:

Mmu.initDescAttrsMeta(attrs0);

attrs0.type = Mmu.DescriptorType_BLOCK; // BLOCK descriptor

attrs0.shareable = 2; // shareable

attrs0.attrIndx = 1; // Non-cache, device memory

// Set the descriptor for each entry in the address range

for (var i = 0x90000000; i < 0xA0000000; i = i + 0x00200000) {

// Each 'BLOCK' descriptor entry spans a 2MB address range

Mmu.setSecondLevelDescMeta(i, i, attrs0);

}

>>The profibus loop has the priority of 4, and If I set it higher then the ethernet doesn't work and software will crash because hwi 41 (CPSW (Ethernet) c0_rx_pend) is not implemented or something like that. The tasks which uses ethernet, which I have two, both have priority of 1.

In addition to your ethernet applications tasks, there are some NDK tasks underneath, which typically have low/normal/high/kernel level priority NDK tasks 3/5/7/11. You may run into issue if setting other tasks .e.g profibus loop higher than NDK normal level.

Can you try to update the hard-coded memory address 0x8200_0000 to 0x9200_0000 in Profibus as noted above to see if it help resolve any memory access conflict between your Ethernet application and Profibus?

Regards, Garrett

Thanks for the hint. Your solution is actually for the AM572x and doesn't work as such for the AM335x.  Here is what worked for me:

- As I only have 256MB DDR, I had to change the address in SwPruss.c ( I left actually 2MB)

int PRUSSDRVMapExtMem(void **address)
{
    *address = (void *)0x8FE00000;
    return 0;

}

Then for the .cfg

// descriptor attribute structure
var DDR3_Attrs = {
    type: Mmu.FirstLevelDesc_SECTION,  // SECTION descriptor
    tex: 0x1,
    bufferable: true,                  // bufferable
    cacheable: true,                   // cacheable
};

// Set the descriptor for each entry in the address range
for (var i=0x80000000; i < 0x8fe00000; i = i + 0x00100000) {
    // Each 'SECTION' descriptor entry spans a 1MB address range
    Mmu.setFirstLevelDescMeta(i, i, DDR3_Attrs);
}

var DDR3_Profibus = {
	type: Mmu.FirstLevelDesc_SECTION,  // SECTION descriptor
    tex: 0x1,
    cacheable: false,                   // cacheable
    shareable : true, 					// shareable
};

// Set the descriptor for each entry in the address range
for (var i=0x8fe00000; i < 0x90000000; i = i + 0x00100000) {
    // Each 'SECTION' descriptor entry spans a 1MB address range
    Mmu.setFirstLevelDescMeta(i, i, DDR3_Profibus);
}

I still have problem that I can't reconfigure the master because the Profibus stack wants to delete a running process which is not allowed. Is there an easy way to make a reset? RTOS doesn't have any reset command.

JHi