Active Errata List * * * * * During UART Reception, Clearing REN May Generate Unexpected IT Timer 2 - Baud Rate Generator - Long Start Time C51 Core - Bad Exit of Power-down in X2 Mode PCA - Incorrect Behavior with CPU X2 Mode Bit of HSB Timer0/1 - Extra Interrupt Errata History Lot Number Errata List All 1, 2, 3, 4, 5 Errata Descriptions 1. During UART Reception, Clearing REN May Generate Unexpected IT 80C51 MCUs AT89C51RD2 AT89C51ED2 During UART reception, if the REN bit is cleared between start bit detection and the end of reception, the UART will not discard the data (RI is set). Workaround Test REN at the beginning of Interrupt routine directly after CLR RI, and run the Interrupt routine code only if REN is set. 2. Errata Sheet Timer 2 - Baud Rate Generator - Long Start Time When Timer 2 is used as a baud rate generator, TH2 is not loaded with RCAP2H at the beginning, then UART is not operational before 10,000 machine cycles. Workaround Add the initialization of TH2 and TL2 in the initialization of Timer 2. 3. C51 Core - Bad Exit of Power-down in X2 Mode When exiting power-down mode by interrupt while CPU is in X2 mode, it leads to bad execution of the first instruction run when CPU restarts. Workaround Set the CPU in X1 mode diretly before entering power-down mode. 4. PCA - Incorrect behavior with CPU X2 mode bit of HSB When starting the microcontroller in X2 mode upon reset with the X2 fuse bit of the HSB, the PCA may not work properly when configured with Timer 0 in X1 mode as clock input. Workaround Set the CPU in X2 mode by software by writing CKCON register at the begin of the application. 5. Timer0/1 - Extra Interrupt When Timer0 is in X1 mode and Timer1 in X2 mode and vice versa, extra interrupt may randomly occur for Timer0 or Timer1. Workaround Use the same mode for the two timers. . Rev. 4257C-8051-01/04 Active UART Bootloader Errata List * API program Data Byte - Incorrect Return Value * API program Data Page - Incorrect Return Value UART Bootloader Errata History Version Number Errata List 0.0 (1.0.0 displayed by FLIP) 1,2 UART Bootloader Errata Description 1. API program Data Byte - Incorrect Return Value The PROGRAM DATA BYTE API returns the `0xXX' instead of 0x00 in ACC, but the programmnig operation is sucessfully completed. 2. API program Data Page- Incorrect Return Value The PROGRAM DATA PAGE API returns the `0xXX' instead of 0x00 in ACC, but the programmnig operation is sucessfully completed. 2 4257C-8051-01/04 Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Regional Headquarters Europe Atmel Sarl Route des Arsenaux 41 Case Postale 80 CH-1705 Fribourg Switzerland Tel: (41) 26-426-5555 Fax: (41) 26-426-5500 Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Atmel Operations Memory 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 RF/Automotive Theresienstrasse 2 Postfach 3535 74025 Heilbronn, Germany Tel: (49) 71-31-67-0 Fax: (49) 71-31-67-2340 Microcontrollers 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 La Chantrerie BP 70602 44306 Nantes Cedex 3, France Tel: (33) 2-40-18-18-18 Fax: (33) 2-40-18-19-60 ASIC/ASSP/Smart Cards 1150 East Cheyenne Mtn. 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