Rainbow Electronics Atmega169L - Manual (Page 281)

281
ATmega169V/L
2514A–AVR–08/02
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 0xFF. At the time the device is
ready for a new byte, the programmed value will read correctly. This is used to deter-
mine when the next byte can be written. This will not work for the value 0xFF, but the
user should have the following in mind: As a chip-erased device contains 0xFF in all
locations, programming of addresses that are meant to contain 0xFF, 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 0xFF, and the user will have to
wait at least t
WD_EEPROM
before programming the next byte. See Table 129 for
t
WD_EEPROM
value.
Figure 128. Serial Programming Waveforms
Table 129. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol Minimum Wait Delay
t
WD_FLASH
4.5 ms
t
WD_EEPROM
9.0 ms
t
WD_ERASE
9.0 ms
MSB
MSB
LSB
LSB
SERIAL CLOCK INPUT
(SCK)
SERIAL DATA INPUT
(MOSI)
(MISO)
SAMPLE
SERIAL DATA OUTPUT
Table 130. Serial Programming Instruction Set
Instruction
Instruction Format
Operation Byte 1 Byte 2 Byte 3 Byte4
Programming Enable 1010 1100 0101 0011 xxxx xxxx xxxx xxxx Enable Serial Programming after
RESET goes low.
Chip Erase 1010 1100 100x xxxx xxxx xxxx xxxx xxxx Chip Erase EEPROM and Flash.
Read Program Memory 0010 H000 000a aaaa bbbb bbbb oooo oooo Read H (high or low) data o from
Program memory at word address a:b.
Load Program Memory Page 0100 H000 000x xxxx xxbb bbbb iiii iiii Write H (high or low) data i to Program
Memory page at word address b. Data
low byte must be loaded before Data
high byte is applied within the same
address.
Write Program Memory Page 0100 1100 000a aaaa bb xx xxxx xxxx xxxx Write Program Memory Page at
address a:b.
Read EEPROM Memory 1010 0000 000x xxaa bbbb bbbb oooo oooo Read data o from EEPROM memory at
address a:b.