AT90S/LS4434 and AT90S/LS8535
89
G: Write Data High Byte
1.
Set BS to “1”. This selects high data.
2.
Give WR a negative pulse. This starts programming of the data byte. RDY/BSY goes low.
3.
Wait until RDY/BSY goes high to program the next byte.
(See Figure 69 for signal waveforms.)
The loaded command and address are retained in the device during programming. For efficient programming, the following
should be considered:
• The command needs only be loaded once when writing or reading multiple memory locations.
• Address high byte needs only be loaded before programming a new 256-word page in the Flash.
• Skip writing the data value $FF, that is, the contents of the entire Flash and EEPROM after a Chip Erase.
These considerations also apply to EEPROM programming and Flash, EEPROM and signature byte reading.
Figure 68.
Programming the Flash Waveforms
Figure 69.
Programming the Flash Waveforms (Continued)
$10
ADDR. HIGH
ADDR. LOW
DATA LOW
DATA
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
OE
12V
DATA HIGH
DATA
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
+12V
OE