83C576 datasheet(39/46 Pages) PHILIPS

39 / 46 page

Philips Semiconductors

Product specification

83C576/87C576

80C51 8-bit microcontroller family

8K/256 OTP/ROM, 6 channel 10-bit A/D, 4 comparators,

failure detect circuitry, watchdog timer

1998 Jun 04

EPROM CHARACTERISTICS

To put the 87C576 in the parallel EPROM programming mode,

PSEN must be held high during power up, then driven low with reset

active. The 87C576 is programmed by using a modified Quick-Pulse

Programming

™ algorithm.

The 87C576 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 87C576 manufactured by

Philips.

Table 3 shows the logic levels for reading the signature byte, 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 38 and 39. Figure 40 shows the

circuit configuration for normal program memory verification.

On-Board Programming (OBP)

The On-Board Programming facility consists of a series of internal

hardware resources coupled with internal firmware to facilitate

remote programming of the 87C576 through the serial port.

The OBP function is invoked by having the EA/VPP pin at the VPP

voltage level at the time that the part exits reset. The OBP function

only requires that the TxD, RxD, VSS, VCC, and VPP pins be

connected to an external circuit in order to use this feature.

The OBP feature provides for the use of a wide range of baud rates

independent of the oscillator frequency used. It is also adaptable to

a wide range of oscillator frequencies. The OBP facility provides for

both auto-echo and no-echo of received characters. The OBP

feature requires that an initial character, an uppercase U, be sent to

the 87C576 to establish the baud rate to be used.

Once baud rate initialization has been performed, the OBP facility

only accepts Intel Hex records. The record-type field of these hex

records are used to indicate either commands or data for the OBP

facility. The maximum number of data bytes in a record is limited to

16 (decimal). These commands/data are summarized below:

Record

Type

Command/Data

Function

Data record, programs the part with data indicated in

record starting with load address in the record

EOF record, no operation

Specify timing parameters

– rec length = 3 bytes

– load address = 0000

– 1st byte = timer count for 50

µs programming pulse

– 2nd byte = timer count for 10

µs delay between pulses

– 3rd byte = 0AH

Program security bits

– rec length = 1 byte

– load address = 0000

– 1st byte = sec bit values (xxxx xxB2B1)

Display contents of USER EPROM array

– rec length = 00

– load address = 0000

Verify security bit status

– rec length = 00

– load address = 0000

Quick-Pulse Programming (Parallel)

The setup for microcontroller quick-pulse programming is shown in

Figure 38. Note that the 87C576 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 3 and 2, as shown in Figure 38. The code byte to be

programmed into that location is applied to port 0. RST, PSEN and

pins of ports 2 and 1 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 39.

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 3 and 2 as

shown in Figure 40. 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 P1.0 and P1.1

need to be pulled to a logic low. The values are:

(030H) = 15H indicates manufactured by Philips

(B6H) =

B6H indicates 87C576

Program/Verify Algorithms

Any algorithm in agreement with the conditions listed in Table 3, and

which satisfies the timing specifications, is suitable.

™Trademark phrase of Intel Corporation.

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