15.15 Row Programming

The largest block of data that can be programmed is a row.

Unlike Word and Quad Word Programming where the SFR memory stores the data source, in Row programming, the SRAM stores the source data. The NVMSRCADDR register is a pointer to the physical location of the source data for Row programming.

Like other Non-Volatile Memory (NVM) programming commands, the NVMADDR register points to the target address of the operation. Row programming always occurs on row boundaries with the row size of 1024. The user can ignore the bits 0 through 9 of the NVMADDR register.

Row Word programming only succeeds if the target address is in a page that is not write-protected. If row programming, erase it before programming any word in it again, even if changing a bit from an erased ‘1’ state to a ‘0’ state.

Array rowbuff is populated with data and programmed into a row located at physical address 0x1008000.

Note:

When assigning the value to the NVMSRCADDR register, convert it to a physical address.
Concurrent access from the Wireless Subsystem and Flash controller using row programming (NVM_RowWrite API) can cause corrupt data. While using row programming, the Wireless Subsystem must be Inactive. Otherwise, use the quad-word programming (NVM_QuadWordWrite API) method.

Row Programming Code Example:

…

unsigned long rowbuff[256]; // example is for a 256 Word row size. 
int x;                         // loop counter

// put some data in the source buffer
      for (x = 0; x < (sizeof(rowbuff) * sizeof (int)); x++)
            ((char *)rowbuff)[x] = x;

// set destination row address
     NVMADDR = 0x1008000;             // row physical address

// set source address. Must be converted to a physical address.
     NVMSRCADDR = (unsigned int)((int)rowbuff & 0x1FFFFFF);

// define Flash operation
      NVMCONbits.NVMOP = 0x3;            // NVMOP for Row programming

// Enable Flash Write
      NVMCONbits.WREN = 1;

// commence programming
      NVMInitiateOperation();            // see Initiate NVM Operation (Unlock Sequence Example)

// Wait for WR bit to clear
      while(NVMCONbits.WR);

// Disable future Flash Write/Erase operations
       NVMCONbits.WREN = 0;

// Check Error Status
       if(NVMCON & 0x3000)            // mask for WRERR and LVDERR bits
      { 
         // process errors
       }
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