SLAZ497H January   2013  – March 2021 MSP430G2744

 

  1. 1Functional Advisories
  2. 2Preprogrammed Software Advisories
  3. 3Debug Only Advisories
  4. 4Fixed by Compiler Advisories
  5. 5Nomenclature, Package Symbolization, and Revision Identification
    1. 5.1 Device Nomenclature
    2. 5.2 Package Markings
      1.      DA38
      2.      RHA40
      3.      YFF49
    3. 5.3 Memory-Mapped Hardware Revision (TLV Structure)
  6. 6Advisory Descriptions
    1. 6.1  BCL12
    2. 6.2  BCL16
    3. 6.3  CPU19
    4. 6.4  CPU45
    5. 6.5  EEM20
    6. 6.6  FLASH24
    7. 6.7  FLASH27
    8. 6.8  FLASH36
    9. 6.9  PORT10
    10. 6.10 SYS15
    11. 6.11 TA12
    12. 6.12 TA16
    13. 6.13 TA21
    14. 6.14 TAB22
    15. 6.15 TB2
    16. 6.16 TB16
    17. 6.17 TB24
    18. 6.18 USCI20
    19. 6.19 USCI21
    20. 6.20 USCI22
    21. 6.21 USCI23
    22. 6.22 USCI24
    23. 6.23 USCI25
    24. 6.24 USCI26
    25. 6.25 USCI27
    26. 6.26 USCI30
    27. 6.27 USCI34
    28. 6.28 USCI35
    29. 6.29 USCI40
    30. 6.30 XOSC5
  7. 7Revision History

6.18 USCI20

USCI Module

Category

Functional

Function

I2C Mode Multi-master transmitter issue

Description

When configured for I2C master-transmitter mode, and used in a multi-master environment, the USCI module can cause unpredictable bus behavior if all of the following four conditions are true:

1 - Two masters are generating SCL
And
2 - The slave is stretching the SCL low phase of an ACK period while outputting NACK on SDA
And
3 - The slave drives ACK on SDA after the USCI has already released SCL, and then the SCL bus line gets released
And
4 - The transmit buffer has not been loaded before the other master continues communication by driving SCL low

The USCI will remain in the SCL high phase until the transmit buffer is written. After the transmit buffer has been written, the USCI will interfere with the current bus activity and may cause unpredictable bus behavior.

Workaround

1 - Ensure that slave doesn't stretch the SCL low phase of an ACK period
Or
2 - Ensure that the transmit buffer is loaded in time
Or
3 - Do not use the multi-master transmitter mode