at90ls4433 ATMEL Corporation, at90ls4433 Datasheet - Page 94

• Manufacturer Part Number: at90ls4433
• Description: At90s4433 8-bit Avr Microcontroller With 4k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Data Polling EEPROM
94
AT90S/LS4433
4. If a Chip Erase is performed (must be done to erase the Flash), wait t
5. The Flash or EEPROM array is programmed one byte at a time by supplying the
6. Any memory location can be verified by using the Read instruction, which returns
7. At the end of the programming session, RESET can be set high to commence
8. Power-off sequence (if needed):
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
38 for t
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
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.
after the instruction, give RESET a positive pulse, and start over from step 2.
See Table 37 on page 97 for t
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
an erased device, no $FFs in the data file(s) need to be programmed. See Table
38 on page 97 for t
the content at the selected address at serial output MISO/PB4.
normal operation.
Set XTAL1 to “0” (if a crystal is not used).
Set RESET to “1”.
Turn V
WD_PROG
CC
power off.
value. As a chip-erased device contains $FF in all locations, program-
WD_PROG
value.
WD_PROG
WD_ERASE
WD_PROG
before programming the next byte. See Table
before transmitting the next instruction. In
value.
P1
$00
P2
$FF
WD_ERASE
1042H–AVR–04/03