PIC24FV16KM204 Datasheet, PDF (77/336 Pages) Microchip Technology – General Purpose, 16-Bit Flash Microcontroller with XLP Technology Data Sheet

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6.4.1.1 Data EEPROM Bulk Erase
To erase the entire data EEPROM (bulk erase), the
address registers do not need to be configured
because this operation affects the entire data
EEPROM. The following sequence helps in performing
a bulk erase:
1. Configure NVMCON to Bulk Erase mode.
2. Clear the NVMIF status bit and enable the NVM
interrupt (optional).
3. Write the key sequence to NVMKEY.
4. Set the WR bit to begin the erase cycle.
5. Either poll the WR bit or wait for the NVM
interrupt (NVMIF is set).
A typical bulk erase sequence is provided in
Example 6-3.
6.4.2 SINGLE-WORD WRITE
To write a single word in the data EEPROM, the
following sequence must be followed:
1. Erase one data EEPROM word (as mentioned in
the previous section) if the PGMONLY bit
(NVMCON<12>) is set to ‘1’.
2. Write the data word into the data EEPROM latch.
3. Program the data word into the EEPROM:
- Configure the NVMCON register to
program one EEPROM word
(NVMCON<5:0> = 0001xx).
- Clear the NVMIF status bit and enable the NVM
interrupt (optional).
- Write the key sequence to NVMKEY.
- Set the WR bit to begin the erase cycle.
- Either poll the WR bit or wait for the NVM
interrupt (NVMIF is set).
- To get cleared, wait until NVMIF is set.
A typical single-word write sequence is provided in
Example 6-4.
EXAMPLE 6-3: DATA EEPROM BULK ERASE
// Set up NVMCON to bulk erase the data EEPROM
NVMCON = 0x4050;
// Disable Interrupts For 5 Instructions
asm volatile ("disi #5");
// Issue Unlock Sequence and Start Erase Cycle
__builtin_write_NVM();
EXAMPLE 6-4: SINGLE-WORD WRITE TO DATA EEPROM
int __attribute__ ((space(eedata))) eeData = 0x1234;
int newData;
// New data to write to EEPROM
/*---------------------------------------------------------------------------------------------
The variable eeData must be a Global variable declared outside of any method
the code following this comment can be written inside the method that will execute the write
-----------------------------------------------------------------------------------------------
*/
unsigned int offset;
// Set up NVMCON to erase one word of data EEPROM
NVMCON = 0x4004;
// Set up a pointer to the EEPROM location to be erased
TBLPAG = __builtin_tblpage(&eeData);
// Initialize EE Data page pointer
offset = __builtin_tbloffset(&eeData);
// Initizlize lower word of address
__builtin_tblwtl(offset, newData);
// Write EEPROM data to write latch
asm volatile ("disi #5");
__builtin_write_NVM();
while(NVMCONbits.WR=1);
// Disable Interrupts For 5 Instructions
// Issue Unlock Sequence & Start Write Cycle
// Optional: Poll WR bit to wait for
// write sequence to complete
 2013 Microchip Technology Inc.
Advance Information
DS33030A-page 77