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278
8154B–AVR–07/09
ATmega16A
26.8.4
Data Polling EEPROM
When a new byte has been written and is being programmed into EEPROM, reading the
address location being programmed will give the value $FF. At the time the device is ready for a
new 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 value $FF, but the user should have the following in
mind: As a chip erased device contains $FF in all locations, programming of addresses that are
meant to contain $FF, can be skipped. This does not apply if the EEPROM is re-programmed
without chip erasing the device. In this case, data polling cannot be used for the value $FF, and
the user will have to wait at least t
WD_EEPROM before programming the next byte. See Table 26-12 for t
WD_EEPROM value.
26.8.5
Serial Programming Instruction set
Table 26-12. Minimum Wait Delay before Writing the Next Flash or EEPROM Location
Symbol
Minimum Wait Delay
t
WD_FUSE
4.5 ms
tWD_FLASH
4.5 ms
tWD_EEPROM
9.0 ms
t
WD_ERASE
9.0 ms
Table 26-13. Serial Programming Instruction Set (Hexadecimal values)
Instruction Format
Byte 1
Byte 2
Byte 3
Byte4
Programming Enable
$AC
$53
$00
Chip Erase (Program Memory/EEPROM)
$AC
$80
$00
Poll RDY/BSY
$F0
$00
data byte out
Load Instructions
Load Extended Address byte
(1)$4D
$00
Extended adr
$00
Load Program Memory Page, High byte
$48
adr MSB
adr LSB
high data byte in
Load Program Memory Page, Low byte
$40
adr MSB
adr LSB
low data byte in
Load EEPROM Memory Page (page access)
(1)$C1
$00
adr LSB
data byte in
Read Instructions
Read Program Memory, High byte
$28
adr MSB
adr LSB
high data byte out
Read Program Memory, Low byte
$20
adr MSB
adr LSB
low data byte out
Read EEPROM Memory
$A0
adr MSB
adr LSB
data byte out
Read Lock bits
$58
$00
data byte out
Read Signature Byte
$30
$00
0000 000aa
data byte out
Read Fuse bits
$50
$00
data byte out
Read Fuse High bits
$58
$08
$00
data byte out
Read Extended Fuse Bits
$50
$08
$00
data byte out