PIC18F1220-I/SO Microchip Technology Inc., PIC18F1220-I/SO Datasheet - Page 65

• Manufacturer Part Number: PIC18F1220-I/SO
• Description: Microcontroller; 4 KB Flash; 256 RAM; 256 EEPROM; 16 I/O; 18-Pin-SOIC
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F1220-I/SO

• A/d Inputs: 7-Channel, 10-Bit
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 16
• Interface: USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin SOIC
• Programmable Memory: 4K Bytes
• Ram Size: 256 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

6.5
The programming block size is 4 words or 8 bytes.
Word or byte programming is not supported.
Table writes are used internally to load the holding
registers needed to program the Flash memory. There
are 8 holding registers used by the table writes for
programming.
FIGURE 6-5:
6.5.1
The sequence of events for programming an internal
program memory location should be:
1.
2.
3.
4.
5.
6.
7.
 2004 Microchip Technology Inc.
TBLPTR = xxxxx0
Read 64 bytes into RAM.
Update data values in RAM as necessary.
Load Table Pointer with address being erased.
Do the row erase procedure (see Section 6.4.1
“Flash Program Memory Erase Sequence”).
Load Table Pointer with address of first byte
being written.
Write the first 8 bytes into the holding registers
with auto-increment.
Set the EECON1 register for the write operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program
• set WREN bit to enable byte writes.
memory;
Writing to Flash Program Memory
FLASH PROGRAM MEMORY WRITE
SEQUENCE
Holding Register
8
TABLE WRITES TO FLASH PROGRAM MEMORY
TBLPTR = xxxxx1
Holding Register
8
Program Memory
Write Register
TBLPTR = xxxxx2
TABLAT
Since the Table Latch (TABLAT) is only a single byte,
the TBLWT instruction must be executed 8 times for
each programming operation. All of the table write
operations will essentially be short writes, because only
the holding registers are written. At the end of updating
8 registers, the EECON1 register must be written to, to
start the programming operation with a long write.
The long write is necessary for programming the
internal Flash. Instruction execution is halted while in a
long write cycle. The long write will be terminated by
the internal programming timer.
8.
9.
10. Write AAh to EECON2.
11. Set the WR bit. This will begin the write cycle.
12. The CPU will stall for duration of the write (about
13. Execute a NOP.
14. Re-enable interrupts.
15. Repeat steps 6-14 seven times to write
16. Verify the memory (table read).
This procedure will require about 18 ms to update one
row of 64 bytes of memory. An example of the required
code is given in Example 6-3.
Holding Register
Disable interrupts.
Write 55h to EECON2.
2 ms using internal timer).
64 bytes.
PIC18F1220/1320
8
TBLPTR = xxxxx7
Holding Register
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