Philips Semiconductors

P89C66X

On-chip Flash 8-bit microcontroller

Errata Sheet

2001 Nov 01

3

FUNCTIONAL DEVIATIONS OF P89C66X, REVISION IDENTIFIER = ‘G’

ISP/IAP.1:

Erase / Erase Verify problem regarding Boot Vector and Status Byte

Introduction:

The P89C66x contains two special Flash registers: the BOOT VECTOR and the STATUS BYTE. At the falling edge of

reset, the P89C66x examines the contents of the Status Byte. If the Status Byte is set to zero, power-up execution starts at

location 0000H, which is the normal start address of the user’s application code. When the Status Byte is set to a value

other than zero, the contents of the Boot Vector is used as the high byte of the execution address and the low byte is set to

00H. The factory default setting is 0FCH, corresponding to the address 0FC00H for the factory masked-ROM ISP boot

loader. A custom boot loader can be written with the Boot Vector set to the custom boot loader. When erasing the Status

Byte or Boot Vector, both bytes are erased at the same time. It is necessary to reprogram the Boot Vector after erasing and

updating the Status Byte.

Problem:

During the Erase operation, the Status Byte and the Boot Vector might not be erased thoroughly enough. Therefore, after

the Status Byte and Boot Vector have been programmed, a read operation may deliver the wrong contents of these

registers.

Workaround:

Depending on the type of Flash programming, the following can be used:

Flash programming using an external Programmer:

Philips has notified the supported parallel programmer vendors.

Check with your programmer vendor to verify that their latest algorithm includes the extra erase cycles for the Boot Vector

and Status Byte.

Flash programming using ISP (In-System Programming):

The following ISP Flash programming tools are available with additional erase cycles for the Boot Vector and the Status

Byte:

1) WinISP Version 2.28 (or higher, from Philips):

2) FlashMagic Version 1.25 (or higher, from Embedded Systems Academy)

(See next page how to download these tools.)

Flash programming using IAP (In-Application Programming):

Use only the latest version of the ISP/IAP Flash Programming Application Note AN461 from October 2001 to do

In-Application Programming. It describes how to add additional erase cycles to the Status Byte / Boot Vector Erase

operation.

(See next page how to download this Application Note.)