st62t62b STMicroelectronics, st62t62b Datasheet - Page 12

• Manufacturer Part Number: st62t62b
• Description: 8-bit Otp/eprom Mcus With A/d Converter, Auto-reload Timer And Eeprom
• Manufacturer: STMicroelectronics

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ST62T52B ST62T62B/E62B
MEMORY MAP (Cont’d)
Additional Notes on Parallel Mode:
If the user wishes to perform parallel program-
ming, the first step should be to set the E2PAR2
bit. From this time on, the EEPROM will be ad-
dressed in write mode, the ROW address will be
latched and it will be possible to change it only at
the end of the programming cycle, or by resetting
E2PAR2 without programming the EEPROM. Af-
ter the ROW address is latched, the MCU can only
“see” the selected EEPROM row and any attempt
to write or read other rows will produce errors.
The EEPROM should not be read while E2PAR2
is set.
As soon as the E2PAR2 bit is set, the 8 volatile
ROW latches are cleared. From this moment on,
the user can load data in all or in part of the ROW.
Setting E2PAR1 will modify the EEPROM regis-
ters corresponding to the ROW latches accessed
after E2PAR2. For example, if the software sets
E2PAR2 and accesses the EEPROM by writing to
addresses 18h, 1Ah and 1Bh, and then sets
E2PAR1, these three registers will be modified si-
multaneously; the remaining bytes in the row will
be unaffected.
Note that E2PAR2 is internally reset at the end of
the programming cycle. This implies that the user
must set the E2PAR2 bit between two parallel pro-
gramming cycles. Note that if the user tries to set
E2PAR1 while E2PAR2 is not set, there will be no
programming cycle and the E2PAR1 bit will be un-
affected. Consequently, the E2PAR1 bit cannot be
set if E2ENA is low. The E2PAR1 bit can be set by
the user, only if the E2ENA and E2PAR2 bits are
also set.
12/68
EEPROM Control Register (EECTL)
Address: EAh — Read/Write
Reset status: 00h
Bit 7 = D7: Unused.
Bit 6 = E2OFF: Stand-by Enable Bit. WRITE ONLY.
If this bit is set the EEPROM is disabled (any access
will be meaningless) and the power consumption of
the EEPROM is reduced to its lowest value.
Bit 5-4 = D5-D4: Reserved. MUST be kept reset.
Bit 3 = E2PAR1: Parallel Start Bit. WRITE ONLY.
Once in Parallel Mode, as soon as the user software
sets the E2PAR1 bit, parallel writing of the 8 adja-
cent registers will start. This bit is internally reset at
the end of the programming procedure. Note that
less than 8 bytes can be written if required, the un-
defined bytes being unaffected by the parallel pro-
gramming cycle; this is explained in greater detail
in the Additional Notes on Parallel Mode overleaf.
Bit 2 = E2PAR2: Parallel Mode En. Bit. WRITE
ONLY. This bit must be set by the user program in
order to perform parallel programming. If E2PAR2
is set and the parallel start bit (E2PAR1) is reset,
up to 8 adjacent bytes can be written simultane-
ously. These 8 adjacent bytes are considered as a
row, whose address lines A7, A6, A5, A4, A3 are
fixed while A2, A1 and A0 are the changing bits,
as illustrated in
reset at the end of any parallel programming pro-
cedure. It can be reset by the user software before
starting the programming procedure, thus leaving
the EEPROM registers unchanged.
Bit 1 = E2BUSY: EEPROM Busy Bit. READ ON-
LY. This bit is automatically set by the EEPROM
control logic when the EEPROM is in program-
ming mode. The user program should test it be-
fore any EEPROM read or write operation; any at-
tempt to access the EEPROM while the busy bit is
set will be aborted and the writing procedure in
progress will be completed.
Bit 0 = E2ENA: EEPROM Enable Bit. WRITE ON-
LY. This bit enables programming of the EEPROM
cells. It must be set before any write to the EEP-
ROM register. Any attempt to write to the EEP-
ROM when E2ENA is low is meaningless and will
not trigger a write cycle.
D7
7
E2O
FF
D5
Table 4.
D4
E2PA
E2PAR2 is automatically
R1
E2PA
R2
E2BU
SY
E2E
NA
0