PIC24F16KL402 Datasheet, PDF (57/260 Pages) Microchip Technology – Low-Power, Low-Cost, General Purpose 16-Bit Flash Microcontrollers with nanoWatt XLP Technology

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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 NVMIF status bit and enable NVM
interrupt (optional).
3. Write the key sequence to NVMKEY.
4. Set the WR bit to begin 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
Section 6.4.1, Erase Data EEPROM) if
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 NVMIF status bit and enable NVM
interrupt (optional).
- Write the key sequence to NVMKEY.
- Set the WR bit to begin erase cycle.
- Either poll the WR bit or wait for the NVM
interrupt (NVMIF 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; // Global variable located in EEPROM
int newData;
// New data to write to EEPROM
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
 2011 Microchip Technology Inc.
DS31037B-page 57