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

BCL12

BCL Module

Category

Functional

Function

Switching RSELx or modifying DCOCTL can cause DCO dead time or a complete DCO stop

Description

After switching RSELx bits (located in register BCSCTL1) from a value of >13 to a value of <12 OR from a value of <12 to a value of >13, the resulting clock delivered by the DCO can stop before the new clock frequency is applied. This dead time is approximately 20 us. In some instances, the DCO may completely stop, requiring a power cycle.

Furthermore, if all of the RSELx bits in the BSCTL1 register are set, modifying the DCOCTL register to change the DCOx or the MODx bits could also result in DCO dead time or DCO hang up.

Workaround

- When switching RSEL from >13 to <12, use an intermediate frequency step. The intermediate RSEL value should be 13.


GUID-20201119-CA0I-XBDP-MZKL-BHL9R3DNGZ9X-low.png


AND

- When switching RSEL from <12 to >13 it's recommended to set RSEL to its default value first (RSEL = 7) before switching to the desired target frequency.

AND
- In case RSEL is at 15 (highest setting) it's recommended to set RSEL to its default value first (RSEL = 7) before accessing DCOCTL to modify the DCOx and MODx bits. After the DCOCTL register modification the RSEL bits can be manipulated in an additional step.

In the majority of cases switching directly to intermediate RSEL steps as described above will prevent the occurrence of BCL12. However, a more reliable method can be implemented by changing the RSEL bits step by step in order to guarantee safe function without any dead time of the DCO.

Note that the 3-step clock startup sequence consisting of clearing DCOCTL, loading the BCSCTL1 target value, and finally loading the DCOCTL target value as suggested in the in the "TLV Structure" chapter of the MSP430x2xx Family User's Guide is not affected by BCL12 if (and only if) it is executed after a device reset (PUC) prior to any other modifications being made to BCSCTL1 since in this case RSEL still is at its default value of 7. However any further changes to the DCOx and MODx bits will require the consideration of the workaround outlined above.