AT89C51AC2 Atmel Corporation, AT89C51AC2 Datasheet - Page 6

• Manufacturer Part Number: AT89C51AC2
• Manufacturer: Atmel Corporation

Specifications of AT89C51AC2

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 40 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Uart: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 62.5
• Sram (kbytes): 1.25
• Eeprom (bytes): 2048
• Self Program Memory: API
• Operating Voltage (vcc): 3.0 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

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
• 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
2. Watchdog and Flash API Starting the Bootloader Execution
3. Autobaud False Start Bit Detection
6
Version Number
1.2 (1.1.2 displayed by FLIP)
1.4
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.
When an application call “__api_start_bootloader” or”__api_start_isp” routines while the watchdog is enabled, when
the watchdog overflow 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.
UART autobaud sequence does not work on 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 on the ‘U’ character.
The autobaud sequence checks 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.
mov SCON, #00h
mov T2CON, #00h
mov RCAP2L, #00h
mov RCAP2H, #00h
mov TL2, #00h
mov TH2, #00h
Errata List
1, 2, 3, 4
1, 2, 3, 5
4159G–8051–05/06