AT90S1200
Figure 31. Programming the Flash Waveforms
DATA
$10
ADDR. HIGH
ADDR.LOW
DATA LOW
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
OE
12V
Figure 32. Programming the Flash Waveforms (Continued)
DATA
DATA HIGH
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
OE
+12V
Reading the Flash
The algorithm for reading the Flash memory is as follows (refer to “Programming the
Flash” for details on command and address loading):
1. A: Load Command “0000 0010”.
2. B: Load Address High Byte ($00 - $01).
3. C: Load Address Low Byte ($00 - $FF).
4. Set OE to “0”, and BS to “0”. The Flash word low byte can now be read at DATA.
5. Set BS to “1”. The Flash word high byte can now be read from DATA.
6. Set OE to “1”.
41
0838H–AVR–03/02
ATMEL [ ATMEL ]
