UPI-41AH Datasheet, PDF (8/20 Pages) Intel Corporation – UNIVERSAL PERIPHERAL INTERFACE 8-BIT SLAVE MICROCONTROLLER

UPI-41AH 42AH
The entire sequence of program pulses and byte
verifications is performed at V_CC ^e 6 0V and V_DD ^e
12 5V When the inteligent Programming cycle has
been completed all bytes should be compared to
the original data with V_CC ^e 5 0 V_DD ^e 5V
Verify
A verify should be performed on the programmed
bits to determine that they have been correctly pro-
grammed The verify is performed with T0 ^e 5V
V_DD ^e 5V EA ^e 12 5V SS ^e 5V PROG ^e 5V
A0 ^e 0V and CS ^e 5V
SECURITY BIT
The security bit is a single EPROM cell outside the
EPROM array The user can program this bit with the
appropriate access code and the normal program-
ming procedure to inhibit any external access to the
EPROM contents Thus the user’s resident program
is protected There is no direct external access to
this bit However the security byte in the signature
row has the same address and can be used to
check indirectly whether the security bit has been
programmed or not The security bit has no effect on
the signature mode so the security byte can always
be examined
SECURITY BIT PROGRAMMING
VERIFICATION
Programming
a Read the security byte of the signature mode
Make sure it is 00H
b Apply access code to appropriate inputs to put
the device into security mode
c Apply high voltage to EA and V_DD pins
d Follow the programming procedure as per the
inteligent Programming Algorithm with known
data on the databus Not only the security bit but
also the security byte of the signature row is pro-
grammed
e Verify that the security byte of the signature
mode contains the same data as appeared on
the data bus (If DB0 – DB7 ^e high the security
byte will contain FFH )
f Read two consecutive known bytes from the
EPROM array and verify that the wrong data are
retrieved in at least one verification If the
EPROM can still be read the security bit may
have not been fully programmed though the se-
curity byte in the signature mode has
Verification
Since the security bit address overlaps the address
of the security byte of the signature mode it can be
used to check indirectly whether the security bit has
been programmed or not Therefore the security bit
verification is a mere read operation of the security
byte of the signature row (0FFH ^e security bit pro-
grammed 00H ^e security bit unprogrammed) Note
that during the security bit programming the reading
of the security byte does not necessarily indicate
that the security bit has been successfully pro-
grammed Thus it is recommended that two consec-
utive known bytes in the EPROM array be read and
the wrong data should be read at least once be-
cause it is highly improbable that random data coin-
cides with the correct ones twice
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