SLAZ185P October   2012  – May 2021 MSP430F2491

 

  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.      PM64
      2.      RGC64
    3. 5.3 Memory-Mapped Hardware Revision (TLV Structure)
  6. 6Advisory Descriptions
    1. 6.1  BCL12
    2. 6.2  BCL13
    3. 6.3  BCL15
    4. 6.4  COMP2
    5. 6.5  CPU19
    6. 6.6  FLASH19
    7. 6.7  FLASH24
    8. 6.8  FLASH25
    9. 6.9  FLASH27
    10. 6.10 FLASH36
    11. 6.11 JTAG23
    12. 6.12 PORT11
    13. 6.13 PORT12
    14. 6.14 TA12
    15. 6.15 TA16
    16. 6.16 TA21
    17. 6.17 TAB22
    18. 6.18 TB2
    19. 6.19 TB16
    20. 6.20 TB24
    21. 6.21 USCI20
    22. 6.22 USCI21
    23. 6.23 USCI22
    24. 6.24 USCI23
    25. 6.25 USCI24
    26. 6.26 USCI25
    27. 6.27 USCI26
    28. 6.28 USCI28
    29. 6.29 USCI30
    30. 6.30 USCI34
    31. 6.31 USCI35
    32. 6.32 USCI40
    33. 6.33 XOSC5
    34. 6.34 XOSC6
    35. 6.35 XOSC8
  7. 7Revision History

6.21 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