Rainbow-electronics ATmega8HVD Manual de usuario descargar pdf (Pagina 137)

137

8052B–AVR–09/08

ATmega4HVD/8HVD

24.8.3 Chip Erase

The Chip Erase will erase the Flash and EEPROM

(1)

memories plus Lock bits. The Lock bits

are not reset until the Program memory has been completely erased. The Fuse bits are not

changed. A Chip Erase must be performed before the Flash and/or EEPROM are re-

programmed.

Note: 1. The EEPROM memory is preserved during Chip Erase if the EESAVE Fuse is programmed.

1. Load command “Chip Erase” (see Table 24-14).

2. Wait after Instr. 3 until SDO goes high for the “Chip Erase” cycle to finish.

3. Load Command “No Operation”.

24.8.4 Programming the Flash

The Flash is organized in pages, see Table 24-10 on page 133. When programming the Flash,

the program data is latched into a page buffer. This allows one page of program data to be

programmed simultaneously. The following procedure describes how to program the entire

Flash memory:

1. Load Command “Write Flash” (see Table 24-14).

2. Load Flash Page Buffer.

3. Load Flash High Address and Program Page. Wait after Instr. 3 until SDO goes high

for the “Page Programming” cycle to finish.

4. Repeat 2 through 3 until the entire Flash is programmed or until all data has been

programmed.

5. End Page Programming by Loading Command “No Operation”.

When writing or reading serial data to the ATmega4HVD/8HVD, data is clocked on the rising

edge of the serial clock, see Figure 24-4, Figure 26-3 and Table 26-9 for details.

Figure 24-3. Addressing the Flash which is Organized in Pages

PROGRAM MEMORY

WORD ADDRESS

WITHIN A PAGE

PAGE ADDRESS

WITHIN THE FLASH

INSTRUCTION WORD

PAG E

PCWORD[PAGEMSB:0]:

PAGEEND

PAG E

PCWORDPCPAGE

PCMSB

PAGEMSB

PROGRAM

COUNTER

1 2 ... 132 133 134 135 136 137 138 139 140 141 142 ... 167 168

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