DocID17922 Rev 6

13/18

STM8AL3xxx STM8L052R8 STM8L1xxx6/8

Silicon limitations

17

Conditions

In Master Receiver mode, when the communication is closed using method 2, the content of

the last read data may be corrupted. The following two sequences are concerned by the

limitation:



Sequence 1: transfer sequence for master receiver when N

2

a)

BTF = 1 (Data N-1 in DR and Data N in shift register)

b)

Program STOP = 1

c)

Read DR twice (Read Data N-1 and Data N) just after programming the STOP bit.



Sequence 2: transfer sequence for master receiver when N

2

a)

BTF = 1 (Data N-2 in DR and Data N-1 in shift register)

b)

Program ACK = 0

c)

Read Data N-2 in DR

d)

Program STOP bit to 1

e)

Read Data N-1.

Description

The content of the shift register (data N) is corrupted (data N is shifted 1 bit to the left) if the

user software is not able to read the data N-1 before the STOP condition is generated on the

bus. In this case, reading data N returns a wrong value.

Workaround 1

–

Sequence 1

When sequence 1 is used to close communication using method 2, mask all active

interrupts between STOP bit programming and Read data N-1.

–

Sequence 2

When sequence 2 is used to close communication using method 2, mask all active

interrupts between Read data N-2, STOP bit programming and Read data N-1.

Workaround 2

Manage I2C RxNE and TxE events with DMA or interrupts of the highest priority level, so

that the condition BTF = 1 never occurs.

Wrong behavior of the I2C peripheral in Master mode after misplaced STOP

Description

on the bus. This can happen in the following conditions:



If a void message is received (START condition immediately followed by a STOP): the

condition on the bus after writing to the START bit in the I2C_CR2 register.



In the other cases of a misplaced STOP, the BERR flag is set in the IC2_CR2 register.

If the START bit is already set in I2C_CR2, the START condition is not correctly

generated on the bus and can create bus errors.