AT90LS4433-4AI datasheet(94/126 Pages) ATMEL

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AT90S/LS4433

1042H–AVR–04/03

ing the third byte of the Programming Enable instruction. Whether or not the

echo is correct, all four bytes of the instruction must be transmitted. If the $53 did

not echo back, give SCK a positive pulse and issue a new Programming Enable

instruction. If the $53 is not seen within 32 attempts, there is no functional device

connected.

If a Chip Erase is performed (must be done to erase the Flash), wait t

WD_ERASE

after the instruction, give RESET a positive pulse, and start over from step 2.

See Table 37 on page 97 for t

WD_ERASE value.

The Flash or EEPROM array is programmed one byte at a time by supplying the

address and data together with the appropriate Write instruction. An EEPROM

memory location is first automatically erased before new data is written. Use

data polling to detect when the next byte in the Flash or EEPROM can be writ-

ten. If polling is not used, wait t

WD_PROG before transmitting the next instruction. In

an erased device, no $FFs in the data file(s) need to be programmed. See Table

38 on page 97 for t

WD_PROG value.

Any memory location can be verified by using the Read instruction, which returns

the content at the selected address at serial output MISO/PB4.

At the end of the programming session, RESET can be set high to commence

normal operation.

Power-off sequence (if needed):

Set XTAL1 to “0” (if a crystal is not used).

Set RESET to “1”.

Turn V

CC power off.

Data Polling EEPROM

When a byte is being programmed into the EEPROM, reading the address location

being programmed will give the value P1 until the auto-erase is finished, and then the

value P2. See Table 34 for P1 and P2 values.

At the time the device is ready for a new EEPROM byte, the programmed value will read

correctly. This is used to determine when the next byte can be written. This will not work

for the values P1 and P2, so when programming these values, the user will have to wait

for at least the prescribed time t

WD_PROG before programming the next byte. See Table

38 for t

WD_PROG value. As a chip-erased device contains $FF in all locations, program-

ming of addresses that are meant to contain $FF can be skipped. This does not apply if

the EEPROM is reprogrammed without first Chip Erasing the device.

Table 34. Read Back Value during EEPROM Polling

Part

AT90S/LS4433

$00

$FF

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