AT93C46E
Table 3-1.
Instruction
READ
EWEN
ERASE
WRITE
ERAL
WRAL
EWDS
Instruction Set for the AT93C46E
Address
SB
1
1
1
1
1
1
1
Op Code
10
00
11
01
00
00
00
x 16
A
5
−
A
0
11XXXX
A
5
−
A
0
A
5
−
A
0
10XXXX
01XXXX
00XXXX
Comments
Reads data stored in memory, at specified address
Write enable must precede all programming modes
Erase memory location A
n
−
A
0
Writes memory location A
n
−
A
0
Erases all memory locations. Valid only at V
CC
= 4.5V to 5.5V
Writes all memory locations. Valid only at V
CC
= 4.5V to 5.5V
Disables all programming instructions
READ (READ):
The Read (READ) instruction contains the address code for the memory loca-
tion to be read. After the instruction and address are decoded, data from the selected memory
location is available at the serial output pin DO. Output data changes are synchronized with the
rising edges of serial clock SK. It should be noted that a dummy bit (logic “0”) precedes the 16-
bit data output string.
ERASE/WRITE ENABLE (EWEN):
To assure data integrity, the part automatically goes into the
Erase/Write Disable (EWDS) state when power is first applied. An Erase/Write Enable (EWEN)
instruction must be executed first before any programming instructions can be carried out.
Please note that once in the EWEN state, programming remains enabled until an EWDS instruc-
tion is executed or V
CC
power is removed from the part.
ERASE (ERASE):
The Erase (ERASE) instruction programs all bits in the specified memory
location to the logical “1” state. The self-timed erase cycle starts once the Erase instruction and
address are decoded. The DO pin outputs the ready/busy status of the part if CS is brought high
after being kept low for a minimum of 250 ns (t
CS
). A logic “1” at pin DO indicates that the
selected memory location has been erased and the part is ready for another instruction.
WRITE (WRITE):
The Write (WRITE) instruction contains the 16 bits of data to be written into
the specified memory location. The self-timed programming cycle, t
WP
, starts after the last bit of
data is received at serial data input pin DI. The DO pin outputs the ready/busy status of the part
if CS is brought high after being kept low for a minimum of 250 ns (t
CS
). A logic “0” at DO indi-
cates that programming is still in progress. A logic “1” indicates that the memory location at the
specified address has been written with the data pattern contained in the instruction and the part
is ready for further instructions.
A ready/busy status cannot be obtained if the CS is brought
high after the end of the self-timed programming cycle, t
WP
.
ERASE ALL (ERAL):
The Erase All (ERAL) instruction programs every bit in the memory array
to the logic “1” state and is primarily used for testing purposes. The DO pin outputs the
ready/busy status of the part if CS is brought high after being kept low for a minimum of 250 ns
(t
CS
). The ERAL instruction is valid only at V
CC
= 5.0V
±
10%.
WRITE ALL (WRAL):
The Write All (WRAL) instruction programs all memory locations with the
data patterns specified in the instruction. The DO pin outputs the ready/busy status of the part if
CS is brought high after being kept low for a minimum of 250 ns (t
CS
). The WRAL instruction is
valid only at V
CC
= 5.0V
±
10%.
5
5207D–SEEPR–1/08
ATMEL [ ATMEL CORPORATION ]
