M95040-125, M95020-125, M95010-125
Instructions
Doc ID 022545 Rev 1
6.5
Read from Memory Array (READ)
As shown in
, to send this instruction to the device, Chip Select (S) is first driven
low. The bits of the instruction byte and address byte are then shifted in, on Serial Data Input
(D). For the M95040, the most significant address bit, A8, is incorporated as bit b3 of the
instruction byte, as shown in
. The address is loaded into an internal
address register, and the byte of data at that address is shifted out, on Serial Data Output
(Q).
If Chip Select (S) continues to be driven low, an internal bit-pointer is automatically
incremented at each clock cycle, and the corresponding data bit is shifted out.
When the highest address is reached, the address counter rolls over to zero, allowing the
Read cycle to be continued indefinitely. The whole memory can, therefore, be read with a
single READ instruction.
The Read cycle is terminated by driving Chip Select (S) high. The rising edge of the Chip
Select (S) signal can occur at any time during the cycle.
The first byte addressed can be any byte within any page.
The instruction is not accepted, and is not executed, if a Write cycle is currently in progress.
Figure 11.
Read from Memory Array (READ) sequence
1.
Depending on the memory size, as shown in
, the most significant address bits
are Don’t Care.
Table 5.
Address range bits
Device M95040-125
M95020-125
M95010-125
Address bits
A8-A0
A7-A0
A6-A0
C
D
AI01440E
S
Q
A7
2
1
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19
A6 A5 A4 A3 A2 A1 A0
A8
20 21 22
7
6
5
4
3
2
0
1
High Impedance
Data Out
Instruction
Byte Address
0
Obsolete Product(s) - Obsolete Product(s)
