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Parallel Programming
Signal Names
AT90S1200
38
the self-timed write instruction in the Serial Programming mode. During programming,
the supply voltage must be in accordance with Table 13.
Table 13. Supply Voltage during Programming
Part
Serial Programming
AT90S1200
2.7 - 6.0V
This section describes how to parallel program and verify Flash program memory,
EEPROM data memory, Lock bits and Fuse bits in the AT90S1200.
Figure 30. Parallel Programming
In this section, some pins of the AT90S1200 are referenced by signal names describing
their function during parallel programming rather than their pin names, see Figure 30
and Table 14. Pins not described in Table 14 are referenced by pin names.
The XA1/XA0 pins determines the action executed when the XTAL1 pin is given a posi-
tive pulse. The coding is shown in Table 15.
When pulsing WR or OE, the command loaded determines the action executed. The
command is a byte where the different bits are assigned functions as shown in Table 16.
Table 14. Pin Name Mapping
Signal Name in
Programming Mode
Pin Name
RDY/BSY
OE
WR
BS
XA0
XA1
DATA
I/O
Function
PD1
O
0: Device is busy programming, 1: Device is ready
for new command
PD2
I
Output Enable (Active low)
PD3
I
Write Pulse (Active low)
PD4
I
Byte Select ("0" selects low byte, "1" selects high
byte)
PD5
I
XTAL Action Bit 0
PD6
I
XTAL Action Bit 1
PB0-7
I/O
Bi-directional Data Bus (Output when OE is low)
Parallel Programming
4.5 - 5.5V
0838H–AVR–03/02
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