ATtiny261/461/861

Table 22-11. XA1 and XA0 Coding

XA1	XA0	Action when XTAL1 is Pulsed
0	0	Load Flash or EEPROM Address (High or low address byte determined by BS1).
0	1	Load Data (High or Low data byte for Flash determined by BS1).
1	0	Load Command
1	1	No Action, Idle

Table 22-12. Command Byte Bit Coding

Command Byte	Command Executed
1000 0000	Chip Erase
0100 0000	Write Fuse bits
0010 0000	Write Lock bits
0001 0000	Write Flash
0001 0001	Write EEPROM
0000 1000	Read Signature Bytes and Calibration byte
0000 0100	Read Fuse and Lock bits
0000 0010	Read Flash
0000 0011	Read EEPROM

22.7Parallel Programming

22.7.1Enter Programming Mode

The following algorithm puts the device in parallel programming mode:

1.Apply 4.5 - 5.5V between VCC and GND.

2.Set RESET to “0” and toggle XTAL1 at least six times.

3.Set the Prog_enable pins listed in Table 22-10 on page 172 to “0000” and wait at least 100 ns.

4.Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns after +12V has been applied to RESET, will cause the device to fail entering programming mode.

5.Wait at least 50 µs before sending a new command.

22.7.2Considerations for Efficient Programming

The loaded command and address are retained in the device during programming. For efficient programming, the following should be considered.

•The command needs only be loaded once when writing or reading multiple memory locations.

•Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the EESAVE Fuse is programmed) and Flash after a Chip Erase.

•Address high byte needs only be loaded before programming or reading a new 256 word window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes reading.

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22.7.3Chip 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 reprogrammed.

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

Load Command “Chip Erase”

1.Set XA1, XA0 to “10”. This enables command loading.

2.Set BS1 to “0”.

3.Set DATA to “1000 0000”. This is the command for Chip Erase.

4.Give XTAL1 a positive pulse. This loads the command.

5.Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low.

6.Wait until RDY/BSY goes high before loading a new command.

22.7.4Programming the Flash

The Flash is organized in pages, see Table 22-7 on page 171. 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:

A. Load Command “Write Flash”

1.Set XA1, XA0 to “10”. This enables command loading.

2.Set BS1 to “0”.

3.Set DATA to “0001 0000”. This is the command for Write Flash.

4.Give XTAL1 a positive pulse. This loads the command.

B. Load Address Low byte

1.Set XA1, XA0 to “00”. This enables address loading.

2.Set BS1 to “0”. This selects low address.

3.Set DATA = Address low byte (0x00 - 0xFF).

4.Give XTAL1 a positive pulse. This loads the address low byte. C. Load Data Low Byte

1.Set XA1, XA0 to “01”. This enables data loading.

2.Set DATA = Data low byte (0x00 - 0xFF).

3.Give XTAL1 a positive pulse. This loads the data byte. D. Load Data High Byte

1.Set BS1 to “1”. This selects high data byte.

2.Set XA1, XA0 to “01”. This enables data loading.

3.Set DATA = Data high byte (0x00 - 0xFF).

4.Give XTAL1 a positive pulse. This loads the data byte.

1.E. Latch Data

2.Set BS1 to “1”. This selects high data byte.

3.Give PAGEL a positive pulse. This latches the data bytes. (See Figure 22-3 for signal waveforms)

F. Repeat B through E until the entire buffer is filled or until all data within the page is loaded.

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While the lower bits in the address are mapped to words within the page, the higher bits address the pages within the FLASH. This is illustrated in Figure 22-2 on page 175. Note that if less than eight bits are required to address words in the page (pagesize < 256), the most significant bit(s) in the address low byte are used to address the page when performing a Page Write.

G. Load Address High byte

1.Set XA1, XA0 to “00”. This enables address loading.

2.Set BS1 to “1”. This selects high address.

3.Set DATA = Address high byte (0x00 - 0xFF).

4.Give XTAL1 a positive pulse. This loads the address high byte. H. Program Page

1.Give WR a negative pulse. This starts programming of the entire page of data. RDY/BSY goes low.

2.Wait until RDY/BSY goes high (See Figure 22-3 for signal waveforms).

I.Repeat B through H until the entire Flash is programmed or until all data has been programmed.

J.End Page Programming

1.1. Set XA1, XA0 to “10”. This enables command loading.

2.Set DATA to “0000 0000”. This is the command for No Operation.

3.Give XTAL1 a positive pulse. This loads the command, and the internal write signals are reset.

Figure 22-2. Addressing the Flash Which is Organized in Pages(1)

PROGRAM

PCMSB

PAGEMSB

PCPAGE

PCWORD

COUNTER

PAGE ADDRESS

WORD ADDRESS

WITHIN THE FLASH

WITHIN A PAGE

PROGRAM MEMORY

PAGE

PCWORD[PAGEMSB:0]:

PAGE

INSTRUCTION WORD

00

01

02

PAGEEND

Note: 1. PCPAGE and PCWORD are listed in Table 22-7 on page 171.

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Figure 22-3. Programming the Flash Waveforms(1)

								F
	A	B	C	D	E	B	C	D	E	G	H
DATA	0x10	ADDR. LOW	DATA LOW	DATA HIGH	XX	ADDR. LOW	DATA LOW	DATA HIGH	XX	ADDR. HIGH	XX

XA1/BS2

XA0

PAGEL/BS1

XTAL1

WR

RDY/BSY

RESET +12V

OE

Note:

1. “XX” is don’t care. The letters refer to the programming description above.

22.7.5Programming the EEPROM

The EEPROM is organized in pages, see Table 22-8 on page 171. When programming the EEPROM, the program data is latched into a page buffer. This allows one page of data to be programmed simultaneously. The programming algorithm for the EEPROM data memory is as follows (refer to ”Programming the Flash” on page 174 for details on Command, Address and Data loading):

1.A: Load Command “0001 0001”.

2.G: Load Address High Byte (0x00 - 0xFF).

3.B: Load Address Low Byte (0x00 - 0xFF).

4.C: Load Data (0x00 - 0xFF).

5.E: Latch data (give PAGEL a positive pulse).

K:Repeat 3 through 5 until the entire buffer is filled.

L:Program EEPROM page

1.Set BS to “0”.

2.Give WR a negative pulse. This starts programming of the EEPROM page. RDY/BSY goes low.

3.Wait until to RDY/BSY goes high before programming the next page (See Figure 22-4 for signal waveforms).

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