RE: nrf9160 Flash access

Randall — Wed, 03 Jun 2020 14:48:15 GMT

I guess I should have replied when I figured it out for myself. With no replies I didn't know if people weren't interested or it was so simple people thought I was an idiot for asking. Because solution was pretty simple. Maybe people could critique my solution.

Anyway, standard nrf9160 definition includes a scratchpad and storage flash partition. Although one could also define their own, I'm going to example using the scratchpad partition.

I create a pointer to constant data;

const char * scratchData;

As well as some defines for access to the scratch area;

#define FLASH_OFFSET DT_FLASH_AREA_IMAGE_SCRATCH_OFFSET
#define FLASH_PAGE_SIZE DT_FLASH_ERASE_BLOCK_SIZE
#define FLASH_SIZE DT_FLASH_AREA_IMAGE_SCRATCH_SIZE

When I initialize, I assign this to the scratchpad partition; as well as getting a device object for the flash;

flashDev = device_get_binding( DT_FLASH_DEV_NAME );

scratchData = (char *)FLASH_OFFSET;

When I erase/write to the section, I use the flash functions

// Erase

flash_write_protection_set( flashDev, false );
flash_erase( flashDev, FLASH_OFFSET, FLASH_PAGE_SIZE );
flash_write_protection_set( flashDev, true );

// Write Block

if (blockOffset + blockSize) > FLASH_SIZE )
{
LOG_ERR( "Write Exceeds Scratchpad Size" );
return(-1);
}

blockOffset += FLASH_OFFSET;
flash_write_protection_set( flashDev, false );
flash_write( flashDev, blockOffset, blockData, blockSize );
flash_write_protection_set( flashDev, true );

Then I can access the block using the scratchData pointer. I use the following configuration variables in prj.conf;

CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y
CONFIG_SOC_FLASH_NRF=y
CONFIG_SOC_FLASH_NRF_EMULATE_ONE_BYTE_WRITE_ACCESS=y

The emulate byte access is so that I can write generic data. I'm not worried about the extra overhead. If you want to handle 4-byte alignment yourself, you don't have to include this.

I deleted a lot of the error handling from my code to make the concept easier to see.

Thanks,

RE: nrf9160 Flash access

Heidi — Wed, 03 Jun 2020 14:36:13 GMT

Hi! I'm sorry for not replying sooner. I just wanted to let you know I'm looking into this and I'll update the case when I have some information for you.

Best regards,

Heidi