SLAA380B December   2007  – September 2018 MSP430F2616 , MSP430F2617 , MSP430F2618 , MSP430F2619

 

  1.   Migrating From MSP430F16x MCUs to MSP430F261x MCUs
    1.     Trademarks
    2. 1 Comparison of MSP430F1xx and MSP430F2xx Families
    3. 2 Hardware Considerations for MSP430F16x to MSP430F261x 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 MSP430F16x to MSP430F261x Migration – Firmware Considerations
      1. 3.1 CPU and Memory Considerations
        1. 3.1.1 Extended Memory Architecture
        2. 3.1.2 Subroutine Parameter Passing and Stack Frame
        3. 3.1.3 MSP430X Instruction Cycle Count Optimizations
        4. 3.1.4 Device Memory Map
        5. 3.1.5 Information Flash Memory
      2. 3.2 Serial Communication – USART Versus USCI
        1. 3.2.1 UART Mode
        2. 3.2.2 SPI Mode
        3. 3.2.3 I2C 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
      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 MSP430F16x and MSP430F261x have different DCO modules. The MSP430F261x 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 MSP430F16x device is in the 800-kHz range, but is in the 1.2-MHz range for an MSP430F261x device. This needs to be considered for applications that run the device using the default DCO settings.
  • On an MSP430F261x, 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 MSP430F16x device in combination with an external clock source to derive a stable high-speed system clock.
  • The MSP430F16x has three bits to control the fundamental frequency range (RSELx in the BCSCTL1 register), and the MSP430F261x has four control bits. Care must be taken when porting algorithms such as a software FLL that modify these bits.
  • In case an MSP430F16x application applies hard-coded DCOx, MODx, and RSELx values to the DCO control registers, they result in a different frequency range on an MSP430F261x.
  • When enabling the external resistor DCO bias feature (by setting DCOR in the BCSCTL2 register), the MSP430F261x DCO start behaving like an MSP430F16x 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]