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80C31 Datasheet(PDF) 21 Page - NXP Semiconductors |
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80C31 Datasheet(HTML) 21 Page - NXP Semiconductors |
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21 / 30 page  Philips Semiconductors Product specification 80C31/80C51/87C51 CMOS single-chip 8-bit microcontrollers 1996 Aug 16 21 EPROM CHARACTERISTICS The 87C51 is programmed by using a modified Quick-Pulse Programming ™ algorithm. It differs from older methods in the value used for VPP (programming supply voltage) and in the width and number of the ALE/PROG pulses. The 87C51 contains two signature bytes that can be read and used by an EPROM programming system to identify the device. The signature bytes identify the device as an 87C51 manufactured by Philips Corporation. Table 3 shows the logic levels for reading the signature bytes, and for programming the program memory, the encryption table, and the security bits. The circuit configuration and waveforms for quick-pulse programming are shown in Figures 13 and 14. Figure 15 shows the circuit configuration for normal program memory verification. Quick-Pulse Programming The setup for microcontroller quick-pulse programming is shown in Figure 13. Note that the 87C51 is running with a 4 to 6MHz 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 EPROM location to be programmed is applied to ports 1 and 2, as shown in Figure 13. The code byte to be programmed into that location is applied to port 0. RST, PSEN and pins of ports 2 and 3 specified in Table 3 are held at the ‘Program Code Data’ levels indicated in Table 3. The ALE/PROG is pulsed low 25 times as shown in Figure 14. To program the encryption table, repeat the 25 pulse programming sequence for addresses 0 through 1FH, using the ‘Pgm Encryption Table’ levels. Do not forget that after the encryption table is programmed, verification cycles will produce only encrypted data. To program the security bits, repeat the 25 pulse programming sequence using the ‘Pgm 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/VPP pin must not be allowed to go above the maximum specified VPP level for any amount of time. Even a narrow glitch above that voltage can cause permanent damage to the device. The VPP source should be well regulated and free of glitches and overshoot. Program Verification If security bit 2 has not been programmed, the on-chip program memory can be read out for program verification. The address of the program memory locations to be read is applied to ports 1 and 2 as shown in Figure 15. The other pins are held at the ‘Verify Code Data’ levels indicated in Table 3. The contents of the address location will be emitted on port 0. External pull-ups 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 locations 030H and 031H, except that P3.6 and P3.7 need to be pulled to a logic low. The values are: (030H) = 15H indicates manufactured by Philips (031H) = 92H indicates 87C51 Program/Verify Algorithms Any algorithm in agreement with the conditions listed in Table 3, and which satisfies the timing specifications, is suitable. Erasure Characteristics Erasure of the EPROM begins to occur when the chip is exposed to light with wavelengths shorter than approximately 4,000 angstroms. Since sunlight and fluorescent lighting have wavelengths in this range, exposure to these light sources over an extended time (about 1 week in sunlight, or 3 years in room level fluorescent lighting) could cause inadvertent erasure. For this and secondary effects, it is recommended that an opaque label be placed over the window. For elevated temperature or environments where solvents are being used, apply Kapton tape Fluorglas part number 2345–5, or equivalent. The recommended erasure procedure is exposure to ultraviolet light (at 2537 angstroms) to an integrated dose of at least 15W-sec/cm2. Exposing the EPROM to an ultraviolet lamp of 12,000 µW/cm2 rating for 20 to 39 minutes, at a distance of about 1 inch, should be sufficient. Erasure leaves the array in an all 1s state. Table 3. EPROM Programming Modes MODE RST PSEN ALE/PROG EA/VPP P2.7 P2.6 P3.7 P3.6 Read signature 1 0 1 1 0 0 0 0 Program code data 1 0 0* VPP 1 0 1 1 Verify code data 1 0 1 1 0 0 1 1 Pgm encryption table 1 0 0* VPP 1 0 1 0 Pgm security bit 1 1 0 0* VPP 1 1 1 1 Pgm security bit 2 1 0 0* VPP 1 1 0 0 NOTES: 1. ‘0’ = Valid low for that pin, ‘1’ = valid high for that pin. 2. VPP = 12.75V +0.25V. 3. VCC = 5V±10% during programming and verification. 4. *ALE/PROG receives 25 programming pulses while VPP is held at 12.75V. Each programming pulse is low for 100µs (±10µs) and high for a minimum of 10 µs. ™Trademark phrase of Intel Corporation. |
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Descripción similar - 80C31 |
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