ST7FLITEU05B3 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
ST7FLITEU05B3 Datasheet PDF : 115 Pages
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ST7LITEU05 ST7LITEU09
DATA EEPROM (Cont’d)
5.3 MEMORY ACCESS
The Data EEPROM memory read/write access
modes are controlled by the E2LAT bit of the EEP-
ROM Control/Status register (EECSR). The flow-
chart in Figure 8 describes these different memory
access modes.
Read Operation (E2LAT=0)
The EEPROM can be read as a normal ROM loca-
tion when the E2LAT bit of the EECSR register is
cleared.
On this device, Data EEPROM can also be used to
execute machine code. Take care not to write to
the Data EEPROM while executing from it. This
would result in an unexpected code being execut-
ed.
Write Operation (E2LAT=1)
To access the write mode, the E2LAT bit has to be
set by software (the E2PGM bit remains cleared).
When a write access to the EEPROM area occurs,
the value is latched inside the 32 data latches ac-
cording to its address.
When PGM bit is set by the software, all the previ-
ous bytes written in the data latches (up to 32) are
programmed in the EEPROM cells. The effective
high address (row) is determined by the last EEP-
ROM write sequence. To avoid wrong program-
ming, the user must take care that all the bytes
written between two programming sequences
have the same high address: only the five Least
Significant Bits of the address can change.
At the end of the programming cycle, the PGM and
LAT bits are cleared simultaneously.
Note: Care should be taken during the program-
ming cycle. Writing to the same memory location
will over-program the memory (logical AND be-
tween the two write access data result) because
the data latches are only cleared at the end of the
programming cycle and by the falling edge of the
E2LAT bit.
It is not possible to read the latched data.
This note is ilustrated by the Figure 10.
Figure 8. Data EEPROM Programming Flowchart
READ MODE
E2LAT=0
E2PGM=0
WRITE MODE
E2LAT=1
E2PGM=0
READ BYTES
IN EEPROM AREA
WRITE UP TO 32 BYTES
IN EEPROM AREA
(with the same 11 MSB of the address)
START PROGRAMMING CYCLE
E2LAT=1
E2PGM=1 (set by software)
CLEARED BY HARDWARE
0
1
E2LAT
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