ATMEGA640 datasheet(352/436 Pages) MICROCHIP

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352

ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

30.9.16

Programming the Flash

Before programming the Flash a Chip Erase must be performed, see “Performing Chip Erase” on page 351.

1. Enter JTAG instruction PROG_COMMANDS.

2. Enable Flash write using programming instruction 2a.

3. Load address Extended High byte using programming instruction 2b.

4. Load address High byte using programming instruction 2c.

5. Load address Low byte using programming instruction 2d.

6. Load data using programming instructions 2e, 2f and 2g.

7. Repeat steps 5 and 6 for all instruction words in the page.

8. Write the page using programming instruction 2h.

9. Poll for Flash write complete using programming instruction 2i, or wait for tWLRH (refer to Table 30-14 on

page 338).

10. Repeat steps 3 to 9 until all data have been programmed.

A more efficient data transfer can be achieved using the PROG_PAGELOAD instruction:

1. Enter JTAG instruction PROG_COMMANDS.

2. Enable Flash write using programming instruction 2a.

3. Load the page address using programming instructions 2b, 2c and 2d. PCWORD (refer to Table 30-7 on

page 328) is used to address within one page and must be written as 0.

4. Enter JTAG instruction PROG_PAGELOAD.

5. Load the entire page by shifting in all instruction words in the page byte-by-byte, starting with the LSB of the

first instruction in the page and ending with the MSB of the last instruction in the page. Use Update-DR to

copy the contents of the Flash Data Byte Register into the Flash page location and to auto-increment the

Program Counter before each new word.

6. Enter JTAG instruction PROG_COMMANDS.

7. Write the page using programming instruction 2h.

8. Poll for Flash write complete using programming instruction 2i, or wait for tWLRH (refer to Table 30-14 on

page 338).

9. Repeat steps 3 to 8 until all data have been programmed.

30.9.17

Reading the Flash

1. Enter JTAG instruction PROG_COMMANDS.

2. Enable Flash read using programming instruction 3a.

3. Load address using programming instructions 3b, 3c and 3d.

4. Read data using programming instruction 3e.

5. Repeat steps 3 and 4 until all data have been read.

A more efficient data transfer can be achieved using the PROG_PAGEREAD instruction:

1. Enter JTAG instruction PROG_COMMANDS.

2. Enable Flash read using programming instruction 3a.

3. Load the page address using programming instructions 3b, 3c and 3d. PCWORD (refer to Table 30-7 on

page 328) is used to address within one page and must be written as 0.

4. Enter JTAG instruction PROG_PAGEREAD.

5. Read the entire page (or Flash) by shifting out all instruction words in the page (or Flash), starting with the

LSB of the first instruction in the page (Flash) and ending with the MSB of the last instruction in the page

(Flash). The Capture-DR state both captures the data from the Flash, and also auto-increments the pro-

gram counter after each word is read. Note that Capture-DR comes before the shift-DR state. Hence, the

first byte which is shifted out contains valid data.

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