Active T89C51AC2, AT89C51AC2 Errata List

A/T89C51AC2 Errata History

A/T89C51AC2 Errata Description

1.

Flash/EEPROM – First Read After Write Disturbed

After a write of more than 32 bytes in the EEPROM and 16 bytes in the User Flash

memory, the read of the first byte may be disturbed if it occurs just after the write.

Workaround

Do not load/write more than 32 bytes at a time for EEPROM memory.

Do not load/write more than 16 bytes at a time for User Flash memory,

OR wait 10 ms before reading the first byte.

2.

Buffer Noise

Large bounces and high noise are generated when buffers are switching (both ris-

ing and falling edges).

Workaround

None.

3.

Double IT on External Falling Edge on INT1 or INT0 in X2 Mode

When the CPU is in X2 mode and Timer1 or Timer 0 in X1 mode (CKCON =

0x7F), IEx flag is not cleared by hardware after servicing interrupt. In this case,

the CPU executes the ISR a second time.

Workaround

The workaround is to clear IEx bit in Interrupt subroutine.

INT1_ISR :

; Interrupt sub routine

CLR IE1

....

Lot Number

Errata List

A00151

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

A00369

1, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13,14

A00367, A00368,

A00396 to A00529

1, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13,14

A00510, all lots from A00588

1, 6, 7, 8, 9, 10, 11, 12, 13,14

80C51 MCUs

AT89C51AC2

T89C51AC2

Errata Sheet