ST6285B View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'ST6285B' PDF : 78 Pages View PDF
ST62T85B/E85B
MEMORY MAP (Cont’d)
1.3.7 EEPROM Description
(PMODE). In BMODE, one byte is accessed at a
EEPROM memory is located in 64-byte pages in
data space. This memory may be used by the user
program for non-volatile data storage.
Data space from 00h to 3Fh is paged as described
in Table 6. EEPROM locations are accessed di-
rectly by addressing these paged sections of data
time, while in PMODE up to 8 bytes in the same
row are programmed simultaneously (with conse-
quent speed and power consumption advantages,
the latter being particularly important in battery
powered circuits).
General Notes:
space.
Data should be written directly to the intended ad-
The EEPROM does not require dedicated instruc-
tions for read or write access. Once selected via the
dress in EEPROM space. There is no buffer mem-
ory between data RAM and the EEPROM space.
Data RAM Bank Register, the active EEPROM When the EEPROM is busy (E2BUSY = “1”)
page is controlled by the EEPROM Control Regis- EECTL cannot be accessed in write mode, it is
ter (EECTL), which is described below.
only possible to read the status of E2BUSY. This
Bit E20FF of the EECTL register must be reset prior implies that as long as the EEPROM is busy, it is
to any write or read access to the EEPROM. If no not possible to change the status of the EEPROM
bank has been selected, or if E2OFF is set, any ac-
) cess is meaningless.
t(s Programming must be enabled by setting the
E2ENA bit of the EECTL register.
uc The E2BUSY bit of the EECTL register is set when
d the EEPROM is performing a programming cycle.
ro Any access to the EEPROM when E2BUSY is set
is meaningless.
P Provided E2OFF and E2BUSY are reset, an EEP-
te ROM location is read just like any other data loca-
le tion, also in terms of access time.
o Writing to the EEPROM may be carried out in two
s modes: Byte Mode (BMODE) and Parallel Mode
Control Register. EECTL bits 4 and 5 are reserved
and must never be set.
Care is required when dealing with the EECTL reg-
ister, as some bits are write only. For this reason,
the EECTL contents must not be altered while ex-
ecuting an interrupt service routine.
If it is impossible to avoid writing to this register
within an interrupt service routine, an image of the
register must be saved in a RAM location, and
each time the program writes to EECTL it must
also write to the image register. The image register
must be written to first so that, if an interrupt oc-
curs between the two instructions, the EECTL will
not be affected.
- Ob Table 6. Row Arrangement for Parallel Writing of EEPROM Locations
duct(s) Byte
0
1
2
3
4
5
6
ro ROW7
P ROW6
te ROW5
ROW4
le ROW3
so ROW2
bROW1
O ROW0
Dataspace
addresses.
Banks 0 and 1.
7
38h-3Fh
30h-37h
28h-2Fh
20h-27h
18h-1Fh
10h-17h
08h-0Fh
00h-07h
Up to 8 bytes in each row may be programmed simultaneously in Parallel Write mode.
The number of available 64-byte banks (1 or 2) is device dependent.
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