AT80C51ID2

1. During UART Reception, Clearing REN May Generate Unexpected IT
During UART reception, if the REN bit is cleared between a 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 just after CLR RI, and run the Interrupt routine code only if REN is set.
2. SPI Interface - Transmission on Master Mode
A 9th bit is transmitted by the interface when the clock rate is set on divide by 2 mode and a positive polarity is selected; the SPR2, SPR1, SPR0 bits are cleared (000) and CPOL = 1 on the SPCON register.
Workaround
Set the clock rate divide by 4 and X2 mode.
3. SPI Interface - SPI SS pin Limitation on Master/Slave
The SS pin of the SPI does not return to an I/O when a One-to-One Master/Slave intercommunication is performed.
Workaround
No
4. SPI - SPI Slave Responding in a Multislave Configuration When Not Selected by the Master and its SPDAT Register Loaded
In a multislave configuration, if the master is sending the Sck and the Tx data to all the slaves, and only one slave is selected, the non-selected slaves respond and generate the end of the transmission interruption (SPIF) if their SPDAT registers are loaded before the transmission.
Workaround
No
5. SPI - SPI Slave Not Responding When Selected and Not Loaded
SPI Slave does not respond when selected by a Master and no Data is loaded to be transmitted. No Rx data is registered and no SPIF interruption is generated at the end of the Transmission.
Workaround
No
6. ALE Disabled Toggles During Internal MOVX
When ALE is disabled, internal MOVX instruction shows toggle of ALE.
Workaround
No
7. Timer 2 - Baud Rate Generator - No IT When TF2 is Set by Software
When timer 2 is used in baud rate generator mode, setting TF2 by software doesn't generate an interrupt.
Workaround
Use timer 1 instead of timer 2 to generate baud rate and interrupt.
8. Timer 2 - Baud Rate Generator - Long Start Time
When timer 2 is used as baud rate generator, TH2 is not loaded with RCAP2H at the beginning, then UART is not operational before 10000 machine cycles.
Workaround
Add the initialisation of TH2 and TL2 in the initialisation of timer 2.
9. SPI Slave Mode/Data Corrupted
When SPI macro is configured in slave reception mode, the SPI block does not handle the good data on the SPI bus.
Workaround
No
10. 32 kHz Oscillator for AT83C51IC2/T80C51ID2 Needs External Feed Back Resistor
Internal feed back resistor is not connected, thus to start up, the 32 kHz Oscillator an external resistor is required.
Workaround
Connect between XTALB1 and XTALB2 a 2 M resistor
11. RB8 Lost With JBC on SCON
On C51 when using JBC instruction on any bit of SCON register, if RB8 bit changes from "1" to "0" during JBC the "0" is lost and RB8 keeps "1".
Workaround
The workaround is to clear RB8.
In a polling algorithm you must clear RB8 at the beginning of the code and after each time it goes to "1".
Interrupt RB8 must be cleared at the beginning of the code and after each time it goes to "1".
12. 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 directly before entering power-down mode.