Auto Programming Procedure - Intel 8XC196NT User Manual

If the security key verification is successful, the routine loads the programming pulse width
(PPW) value from the external EPROM into the internal PPW register. It then asserts PACT#, in-
dicating that programming has begun. (PACT# is also active during reset, although no program-
ming is in progress.) PVER is initially asserted and remains asserted unless an error is detected,
in which case it is deasserted.
The routine then reads the contents of the external EPROM, beginning at 4000H. It skips any
word that contains FFFFH (unprogrammed state). When it reads a word that contains any value
other than FFFFH, the routine calls the modified quick-pulse algorithm, which writes that value
to the OTPROM, using the appropriate number of pulses for the device, then verifies the result.
The routine repeats this activity until the entire OTPROM is programmed, then deasserts PACT#
and enters an endless loop.

15.9.4 Auto Programming Procedure

If a glitch or reset occurs while programming the security key and lock bits, an unknown security
key might accidentally be written, rendering the device inaccessible for further programming. To
minimize this possibility, follow this recommended programming procedure.
All addresses are given for the circuit shown in Figure 15-12 on page 15-26. If
you choose a different circuit, you must adjust the addresses accordingly.
1. Using a blank EPROM device, follow these steps to skip programming of CCB0 and
program the rest of the OTPROM array, including the security key.
— Place the programming pulse width (PPW) in external EPROM locations 14H–15H.
— Leave the external CCB0 location (4018H) unprogrammed (0FFFFH).
— Place the appropriate CCB1 value at external location 401AH.
— Place the appropriate CCB2 value at external location 401CH.
— Place the security key to be programmed in external EPROM locations 4020H–402FH.
— Place the value 20H in external EPROM locations 4019H, 401BH, 401DH, and 401FH
(for the reserved OTPROM locations that require this value).
— Place the desired code in the remaining external EPROM locations 4000H and above
(see Table 15-10 on page 15-27).
— Execute the power-up sequence (page 15-14) to initiate auto programming.
— When programming is complete, execute the powerdown sequence (page 15-14) before
continuing to step 2.
PROGRAMMING THE NONVOLATILE MEMORY
NOTE
15-29