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

3.3.2 Digitally Controlled Oscillator (DCO)

The F13x/F14x and F23x/F24x have different DCO modules. The F23x/F24x DCO offers higher accuracy, an extended frequency range allowing operation of the device up to the maximum operating frequency, and factory-provided calibration constants to facilitate the design of systems that operate without external clock sources.

The key points that should be considered during migration are:

  • The default DCO frequency of an F13x/F14x MCU is in the 800-kHz range, but it is in the 1.2-MHz range for an F23x/F24x MCU. This needs to be considered for applications that run the device using the default DCO settings.
  • On an F23x/F24x, consider loading any of the factory-provided DCO calibration constants into the DCO to achieve a deterministic and stable output frequency. The use of the DCO calibration constants may omit the need for software-FLL algorithms used on an F13x/F14x MCU in combination with an external clock source to derive a stable high-speed system clock.
  • The F13x/F14x has three bits to control the fundamental frequency range (RSELx in the BCSCTL1 register), and the F23x/F24x has four control bits. Care must be taken when porting algorithms such as a software FLL that modify these bits.
  • If an F13/F14x application applies hard-coded DCOx, MODx, and RSELx values to the DCO control registers, this results in a different frequency range on an F23x/F24x.
  • When enabling the external resistor DCO bias feature (by setting DCOR in the BCSCTL2 register), the F23x/F24x DCO starts behaving like an F13x/F14x DCO. In this mode, the same bit settings and external bias resistors result in the same frequency being generated. See the device-specific data sheets for further details. [3][4]