Similar to other issues I have had with other SDK samples (FatFS/SDcard), it seems that caching causes problems with USB device samples.
If I switch one of the samples (such as: dev_hid_mouse_bm) to use SRAM_OC as location of global vars, then USB will fail to enumerate.
I have also tried setting the config buffer to be cacheable in usb_device_config.h, but that causes USB device initialization to fail completely.
How can I use the USB stack when running from OCRAM?
Hello guys,
In cases when a cacheable RAM region is being used as main RAM for the application it will be necessary to relocate the USB descriptors and data to a non cacheable memory. The following changes in the project will take care of this relocation:
- In the usb_misc.h file update these definitions to the following, changes in bold:
#else
#define USB_GLOBAL USB_LINK_USB_GLOBAL_BSS
#define USB_BDT USB_LINK_USB_BDT_BSS
#define USB_DMA_DATA_NONINIT_SUB USB_LINK_NONCACHE_NONINIT_DATA
#define USB_DMA_DATA_INIT_SUB
#define USB_CONTROLLER_DATA USB_LINK_NONCACHE_NONINIT_DATA
#endif
- In the project properties, inside the managed linker script configurations add the following Extra linker script input sections:
With the above configuration, the USB descriptors and data will be placed in the SRAM_DTC region, the same changes apply if you want to use the Non cacheable SDRAM region, you just need to change the region you want to use in the configuration above.
Hope this helps.
Regards,
Carlos Mendoza
I tried defining sections to match what is in the USB macros of usb_misc.h, but it still didn't fix the issue.
Hello guys,
In cases when a cacheable RAM region is being used as main RAM for the application it will be necessary to relocate the USB descriptors and data to a non cacheable memory. The following changes in the project will take care of this relocation:
- In the usb_misc.h file update these definitions to the following, changes in bold:
#else
#define USB_GLOBAL USB_LINK_USB_GLOBAL_BSS
#define USB_BDT USB_LINK_USB_BDT_BSS
#define USB_DMA_DATA_NONINIT_SUB USB_LINK_NONCACHE_NONINIT_DATA
#define USB_DMA_DATA_INIT_SUB
#define USB_CONTROLLER_DATA USB_LINK_NONCACHE_NONINIT_DATA
#endif
- In the project properties, inside the managed linker script configurations add the following Extra linker script input sections:
With the above configuration, the USB descriptors and data will be placed in the SRAM_DTC region, the same changes apply if you want to use the Non cacheable SDRAM region, you just need to change the region you want to use in the configuration above.
Hope this helps.
Regards,
Carlos Mendoza
Carlos - that answer was super helpful for me to get stated. I just would like another option. The NonCacheable section could also assigned to the OCRAM memory region.
- Set up another region of OCRAM (note - 0x10000 is really much more than is needed)
- Like Carlos, use the "NonCacheable" description on the new region
- Setup the MPU to block cache access to a MPU region in board.c
/* Region 5 setting */
MPU->RBAR = ARM_MPU_RBAR(5, 0x20210000);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 0, 1, 0, ARM_MPU_REGION_SIZE_64KB);
- Then follow Carlos' first step and add USB_LINK_NONCACHE_NONINIT_DATA in usb_misc.h
This example kind of fragments the memory, but it should work well enough to get started running the USB demo completely in OCRAM.
were you able to run the USB code on SRAM_OC with the above changes?.
i have been trying the above changes, but the USB enumeration is failing.
this is my board.c changes
/* Region 5 setting: Memory with Normal type, not shareable, outer/inner write back */
MPU->RBAR = ARM_MPU_RBAR(5, 0x00000000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 1, 1, 0, ARM_MPU_REGION_SIZE_128KB);
/* Region 6 setting: Memory with Normal type, not shareable, outer/inner write back */
MPU->RBAR = ARM_MPU_RBAR(6, 0x20000000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 1, 1, 0, ARM_MPU_REGION_SIZE_128KB);
/* Region 7 setting: Memory with Normal type, not shareable, outer/inner write back */
MPU->RBAR = ARM_MPU_RBAR(7, 0x20200000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 1, 1, 0, ARM_MPU_REGION_SIZE_256B-ARM_MPU_REGION_SIZE_32KB);
/*Region 11 for sram oc non cache area */
MPU->RBAR = ARM_MPU_RBAR(11, 0x20238000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 0, 1, 0, ARM_MPU_REGION_SIZE_32KB);
/* Region 8 setting: Memory with Normal type, not shareable, outer/inner write back */
MPU->RBAR = ARM_MPU_RBAR(8, 0x80000000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 1, 1, 0, ARM_MPU_REGION_SIZE_32MB);
while ((size >> i) > 0x1U)
{
i++;
}
if (i != 0)
{
/* The MPU region size should be 2^N, 5<=N<=32, region base should be multiples of size. */
assert(!(nonCacheStart % size));
assert(size == (uint32_t)(1 << i));
assert(i >= 5);
/* Region 9 setting: Memory with Normal type, not shareable, non-cacheable */
MPU->RBAR = ARM_MPU_RBAR(9, nonCacheStart);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 1, 0, 0, 0, 0, i - 1);
}
/* Region 10 setting: Memory with Device type, not shareable, non-cacheable */
MPU->RBAR = ARM_MPU_RBAR(10, 0x40000000);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 2, 0, 0, 0, 0, ARM_MPU_REGION_SIZE_4MB);
/* Enable MPU */
ARM_MPU_Enable(MPU_CTRL_PRIVDEFENA_Msk);
my usb_misc.h changes
#define USB_CONTROLLER_DATA USB_LINK_NONCACHE_NONINIT_DATA
#else
#define USB_GLOBAL USB_LINK_USB_GLOBAL_BSS
#define USB_BDT USB_LINK_USB_BDT_BSS
#define USB_DMA_DATA_NONINIT_SUB USB_LINK_NONCACHE_NONINIT_DATA
#define USB_DMA_DATA_INIT_SUB
#define USB_CONTROLLER_DATA USB_LINK_NONCACHE_NONINIT_DATA
#endif
my linker setttings
my mcu settings
am I missing anything?
