SLAA381C December   2007  – September 2018 MSP430F233 , MSP430F235 , MSP430F2410 , MSP430F247 , MSP430F248 , MSP430F249

 

  1.   Migrating From MSP430F13x and MSP430F14x MCUs to MSP430F23x and MSP430F24x MCUs
    1.     Trademarks
    2. 1 Comparison of MSP430F1xx and MSP430F2xx Families
    3. 2 Hardware Considerations for F13x/F14x to F23x/F24x Migration
      1. 2.1 Device Package and Pinout
      2. 2.2 Current Consumption
      3. 2.3 Operating Frequency and Supply Voltage
      4. 2.4 Device Errata
    4. 3 Firmware Considerations for F13x/F14x to F23x/F24x Migration
      1. 3.1 Memory Considerations
        1. 3.1.1 Device Memory Map
        2. 3.1.2 Information Flash Memory
      2. 3.2 Serial Communication – USART and USCI
        1. 3.2.1 UART Mode
        2. 3.2.2 SPI Mode
      3. 3.3 Clock System
        1. 3.3.1 LFXT1 and XT2 Oscillators
        2. 3.3.2 Digitally Controlled Oscillator (DCO)
      4. 3.4 Bootloader (BSL)
      5. 3.5 Interrupt Vectors
      6. 3.6 Beware of Reserved Bits!
      7. 3.7 Timers
      8. 3.8 Analog Comparator
    5. 4 References
  2.   Revision History

3.3.1 LFXT1 and XT2 Oscillators

The F23x/F24x oscillator blocks supersede the ones found on F13x/F14x MCUs. The F23x/F24x oscillators can operate with the same low- and high-frequency oscillators and clock sources, but they consume less power while providing increased robustness. In addition, built-in software-configurable crystal load capacitors are provided in low-frequency (LF) mode. The power-on default for the effective load capacitance in LF mode is 6 pF, which is in line with the F13x/F14x LF oscillator.

When migrating designs that use external crystals or clock sources, items to keep in mind are:

  • The capability of F23x/F24x MCUs to detect low-frequency oscillator failures and indicate them by setting the LFXT1OF flag results in another path for the global oscillator fault flag (OFIFG) to become set. This may prevent the CPU from being clocked by a crystal or an external clock source in certain scenarios.
  • If the existing F13x/F14x design uses an external 32-kHz crystal for low-power mode operation and periodic wakeup (LPM3), and crystal-accurate precision is not required, the F23x/F24x built-in VLO oscillator can be used instead, resulting in the elimination of the external crystal and a reduced LPM3 power consumption. The VLO frequency is 12 kHz (data sheet typical value) but can be measured and virtually calibrated. For more details, see reference [5].
  • If an external digital clock source is used, the F23x/F24x newly available direct digital clock input mode should be used (by setting the LFXT1S1 and LFXT1S0 control bits).
  • If the existing F13x/F14x design uses a high-frequency crystal or resonator on LFXT1 or XT2, the appropriate frequency range must be configured in the F23x/F24x clock system control register BCSCTL3. The default range setting is for use with 0.4-MHz to 1-MHz crystals or resonators. See the Basic Clock Module+ user's guide chapter for further details. [2]