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4131J–CAN–05/06

T89C51CC01 Errata Sheet

Active UART Bootloader Errata List

• Timer 2 and UART Are Not Stopped

• Watchdog and Flash API Starting the Bootloader Execution

• Autobaud False Start Bit Detection

• Boot Process Compatibility

• Flash API ’__api_wr_code_page’ with 0 Data in Length Parameter Field

UART Bootloader Errata History

UART Bootloader Errata Description

1.

Timer 2 and UART Are Not Stopped

When the bootloader receives the command ’Start Application’ (LJMP 0), the Timer 2 and the UART are not stopped.

Workaround

The application must have in its setup function a reset of Timer 2 and UART.

mov SCON, #00h

mov T2CON, #00h

mov RCAP2L, #00h

mov RCAP2H, #00h

mov TL2, #00h

mov TH2, #00h

2.

Watchdog and Flash API Starting the Bootloader Execution

When an application call ’__api_start_bootloader’ or ’__api_start_isp’ routines while the watchdog is enabled, when the

watchdog overflows it will restart the application instead of the bootloader.

Workaround

Set BLJB(=1) before calling the __api_start_bootloader or __api_start_isp if the watchdog is used.

3.

Autobaud False Start Bit Detection

UART autobaud sequence does not work in some special UARTs.

Some laptops have the UART TX line set to 0 when unused (COM port closed), this results in a false baud rate calcu-

lation in the ‘U’ character.

The autobaud sequence checkes for a ‘0’ state (not a falling edge) on the Rx line of the UART microcontroller to detect

the ‘start’ bit of the ‘U’ synchro character.

As this line is ‘0’ by default when COM port is closed, the autobaud routine starts its baudrate calculation at the opening

sequence of the UART.

Workaround

A ‘Special Sync’ can be used with ‘FLIP’ software.

In this case, the open port event and the ‘U’ sent are dissociated. The user must first open the COM port with the ‘con-

nect’ button, then reset the hardware and finally push the ‘sync’ button.

4.

Boot Process Compatibility

There are some differences between Boot process of bootloader 1.2 and newer versions (see below).

Version Number

Errata List

1.2 (1.1.2 displayed by FLIP)

1, 2, 3

1.4 (Current)

1, 2, 3, 4,5