Table 124. Command Byte Bit Coding

Command Byte	Command Executed
0000 1000	Read Signature Bytes and Calibration byte
0000 0100	Read Fuse and Lock Bits
0000 0010	Read Flash
0000 0011	Read EEPROM

Table 125. No. of Words in a Page and no. of Pages in the Flash

Flash Size	Page Size	PCWORD	No. of Pages	PCPAGE	PCMSB
64K words (128K bytes)	128 words	PC[6:0]	512	PC[15:7]	15

Table 126. No. of Words in a Page and no. of Pages in the EEPROM

EEPROM Size	Page Size	PCWORD	No. of Pages	PCPAGE	EEAMSB
4K bytes	8 bytes	EEA[2:0]	512	EEA[11:3]	8

Parallel Programming

Enter Programming Mode	The following algorithm puts the device in parallel programming mode:
	1.	Apply 4.5 - 5.5 V between VCC and GND.
	2.	Set		to “0” and toggle XTAL1 at least 6 times
			RESET
	3.	Set the Prog_enable pins listed in Table 122 on page 283 to “0000” and wait at
		least 100 ns.
	4.	Apply 11.5 - 12.5V to				Any activity on Prog_enable pins within 100 ns
					RESET.
		after +12V has been applied to					RESET,	will cause the device to fail entering pro-
		gramming mode.
Considerations for Efficient	The loaded command and address are retained in the device during programming. For
Programming	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 $FF, 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.
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 is 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”.

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		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							goes low.
				WR	a negative pulse. This starts the Chip Erase. RDY/BSY
		6.					goes high before loading a new command.
			Wait until RDY/BSY
Programming the Flash		The Flash is organized in pages, see Table 124 on page 283. 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 pro-
		gram 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 ($00 - $FF).

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 ($00 - $FF).

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 ($00 - $FF).

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

E. Latch Data

1.Set BS1 to '1'. This selects high data byte.

2.Give PAGEL a positive pulse. This latches the data bytes. (See Figure 137 for signal waveforms)

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

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 136 on page 286. Note

that if less than 8 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 ($00 - $FF).

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

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H. Program Page

1.Set BS1 = “0”

2.Give WR a negative pulse. This starts programming of the entire page of data. RDY/BSYgoes low.

3.Wait until RDY/BSY goes high. (See Figure 137 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 136. Addressing the Flash which is Organized in Pages

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 125 on page 284.

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Figure 137. Programming the Flash Waveforms

							F
	A	B	C	D	E	B	C	D	E	G	H
DATA	$10	ADDR. LOW	DATA LOW	DATA HIGH	XX	ADDR. LOW	DATA LOW	DATA HIGH	XX	ADDR. HIGH	XX

XA1

XA0

BS1

XTAL1

WR

RDY/BSY

RESET +12V

OE

PAGEL

BS2

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

Programming the EEPROM The EEPROM is organized in pages, see Table 125 on page 284. 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 285 for details on

Command, Address and Data loading):

1.A: Load Command “0001 0001”.

2.G: Load Address High Byte ($00 - $FF)

3.B: Load Address Low Byte ($00 - $FF)

4.C: Load Data ($00 - $FF)

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 BS1 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 138 for signal waveforms)

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