C501 Datasheet, PDF (26/48 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C501
Quick-Pulse Programming
The setup for microcontroller quick-pulse programming is shown in figure 10. Note that the C501-
1E is running with a 4 to 6 MHz oscillator The reason the oscillator needs to be running is that the
device is executing internal address and program data transfers.
The address of the OTP memory location to be programmed is applied to port 1 and 2 as shown in
figure 10. The code byte to be programmed into that location is applied to port 0. RESET, PSEN
and pins of port 2 and 3 specified in table 11 are held at the “Program code data“ levels. The ALE/
PROG signal is pulsed low 25 times as shown in figure 11.
For programming of the encryption table, the 25 pulse programming sequence must be repeated for
addresses 0 through 1FH, using the “Program encrytion table“ levels. After the encryption table is
programmed, verification cycles will produce only encrypted data.
For programming of the security bits, the 25 pulse programming sequence must be repeat using the
“Program security bit“ levels. After one security bit is programmed, further programming of the code
memory and encryption table is disabled. However, the other security bit can still be programmed.
Note that the EA/V_PP pin must not be allowed to go above the maximum specified V_PP level. for any
amount of time. Even a narrow glitch above that voltage can cause permanent damage to the
device. The V_PP source should be well regulated and free of glitches and overshoots.
Program Verification
If security bit 2 has not been programmed, the on-chip OTP program memory can be read out for
program verification. The address of the OTP program memory locations to be read is applied to
ports 1 and 2 as shown in figure 12. The other pins are held at the “Verify code data“ levels
indicated in table 11. The contents of the address location will be emitted on port 0. External pullups
are required on port 0 for this operation.
If the encryption table has been programmed, the data presented at port 0 will be the exclusive NOR
of the program byte with one of the encryption bytes. The user will have to know the encryption
table contents in order to correctly decode the verification data. The encryption table itself cannot be
read out.
Reading the SIgnature Bytes
The signature bytes are read by the same procedure as a normal verification of loctions 30H and
31H, except that P3.6 and P3.7 need to be pulled to a logic low. The values are :
30H = E0H indicates manufacturer
31H = 71H indicates C501-1E
Semiconductor Group
26
1997-04-01