8051AH Datasheet, PDF (14/21 Pages) Intel Corporation – MCS51 8-BIT CONTROL-ORIENTED MICROCONTROLLERS

MCS@51 CONTROLLER
EPROM CHARACTERISTICS
Mode
RST
Program
1
Verify
1
Security Set
1
NOTE:
“1” = logichighfor that pin
“O” = logiclowfor that pin
“X” = “don’t care”
Table3. EPROMProgrammingModea
PSEN ALE
m
P2.7
0
o*
VPP
1
0
1
1
0
0
o*
VPP
1
P2.6
0
0
1
“VPP” = +21V *0.5V
*ALEis pulsedlowfor 50 ms
P2.5
x
x
x
P2.4
x
x
x
PROGRAMMING THE 8751H
To be programmed, the part must be running with a
4 to 6 MHz oscillator. (The reason the oscillator
needs to be running is that the internal bus is being
used to transfer address and program data to appro-
priate internal registers.) The address of an EPROM
location to be programmed is applied to Port 1 and
pins P2.O-P2.3 of Port 2, while the code byte to be
programmed into that location is applied to Port O.
The other Porl 2 pins, and RST, PSEN, and ~/Vpp
should be held at the “Program” levels indicated in
Table 3. ALE/PROG is pulsed low for 50 ms to pro-
gram the code byte into the addressed EPROM lo-
cation. The setup is shown in Figure 5.
Normally ~~is
held at a logic highflntil just
before ALE/PROG is to be pulsed. Then EA/Vpp is
raised to +21 V, ALE/PROG is pulsed, and then
~/Vpp is returned to a logic high. Waveforms and
detailed timing specifications are shown in later sec-
tions of this data sheet.
+5V
Note that the ~/VPP pin must not be allowed to go
above the maximum specified VPP level of 21.5V for
any amount of time. Even a narrow glitch above that
voltage Ievei can cause permanent damage to the
device. The VPP source should be well regulated
and free of glitches.
Program Verification
If the Security Bit has not been programmed, the on-
chip Program Memory can be read out for verifica-
tion purposes, if desired, either during or after the
programming operation. The address of the Program
Memory location to be read is appiied to Port 1 and
pins P2.O-P2.3. The other pins should be held at the
“Verify” Ieveis indicated in Tabie 3. The contents of
the addressed location will come out on Port O. Ex-
ternal pullups are required on Port O for this opera-
tion.
The setup, which is shown in Figure 6, is the same
as for programming the EPROM except that pin P2.7
is held at a logic low, or may be used as an active-
Iow read strobe
Vcc
+5V
AOOR ^{A&b? p?}
?
—FFH
P2.0–
w
PGM DATA
Vcc
U–All
P2.3
mu
‘=’’-”T‘LCEAlR=$E=J-=E ^a
8751H
—FFH
w+
~ . ,,W,, CARE,. ^x -
W51H
~~b
DATA
(USE 10K
PULLUPS]
U^Vlli
4-SUN* n
P2.7
XTAU
XTAL1
Vss
5
RST
PSEN
F&vPP
VIH1
ENAS4E
X-9
VIL d
.
J-
4-6 MHZm
P2.5
P2.S
P2 7
XTAU
XTAL1
ALE
VIH
G
RST h VIH1
.
.
Vss
PSEN
27231 a-1 I
.
Figure5. ProgrammingConfiguration
27231S-12
Figure6. ProgramVerification
14