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
Parallel Programming
AT90S1200
2.7 - 6.0V
4.5 - 5.5V
Parallel Programming
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
Signal Names
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 I/O Function
RDY/BSY
PD1
O
0: Device is busy programming, 1: Device is ready
for new command
OE
WR
BS
PD2
PD3
PD4
I
I
I
Output Enable (Active low)
Write Pulse (Active low)
Byte Select (“0” selects low byte, “1” selects high
byte)
XA0
XA1
PD5
PD6
I
I
XTAL Action Bit 0
XTAL Action Bit 1
DATA
PB0-7
I/O Bi-directional Data Bus (Output when OE is low)
38
AT90S1200
0838H–AVR–03/02
ATMEL [ ATMEL ]
