Table of Contents
Advertisement
16.7.2.1
Power-up Sequence
1.
Hold the RESET# pin low while V
time.
2.
After V
and the oscillator stabilize, continue to hold the device in reset and apply V
CC
voltage to EA#.
3.
After EA# stabilizes, apply V
4.
Set the PMODE value to select a programming algorithm.
5.
Bring the RESET# pin high.
6.
Complete the selected programming algorithm.
16.7.2.2
Power-down Sequence
1.
Assert the RESET# signal and hold it low throughout the powerdown sequence.
2.
Remove the V
PP
3.
Remove the V
PP
4.
Turn off the V
CC
16.8 SLAVE PROGRAMMING MODE
Slave programming mode allows you to program and verify the entire OTPROM array, including
the PCCBs and UPROM bits, by using an EPROM programmer.
In this mode, ports 3 and 4 serve as the PBUS, transferring commands, addresses, and data. The
least-significant bit of the PBUS (P3.0) controls the command (1 = program word; 0 = dump
word) and the remaining 15 bits contain the address of the word to be programmed or dumped.
Some port 2 pins provide handshaking signals. The AINC# signal controls whether the address
is automatically incremented, enabling programming or dumping sequential OTPROM locations.
This speeds up the programming process, since it eliminates the need to generate and decode each
sequential address.
If a glitch or reset occurs during programming of the security key, an unknown
security key might accidentally be written, rendering the device inaccessible
for further programming. To prevent this possibility during slave
programming, program the rest of the OTPROM array before you program the
CCB security-lock bits (CCB0.6 and CCB0.7).
CC
voltage (+12.5V) to the V
PP
voltage from the V
pin and allow the pin to float.
PP
voltage from the EA# pin and allow the pin to float.
supply and allow time for it to reach 0 volts.
NOTE
PROGRAMMING THE NONVOLATILE MEMORY
stabilizes. Allow V
PP
pin.
PP
and EA# to float during this
PP
16-15
Advertisement
Table of Contents
