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

3.3.1 LFXT1 and XT2 Oscillators

The MSP430F261x oscillator blocks supersede the ones found on MSP430F16x devices. The MSP430F261x oscillators can operate with the same low- and high-frequency oscillators and clock sources but 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 MSP430F16x LF oscillator.

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

  • The capability of MSP430F261x devices to detect low-frequency oscillator failures and indicate them by setting the LFXT1OF flag results in another path for the global oscillator fault flag to become set (OFIFG). This may prevent the CPU from being clocked by a crystal or an external clock source in certain scenarios.
  • In case the existing MSP430F16x design uses an external 32-kHz crystal for low-power mode operation and periodic wakeup (LPM3), and crystal-accurate precision is not required, the MSP430F261x 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].
  • In case an external digital clock source is used, the MSP430F261x newly available direct digital clock input mode should be used (by setting the LFXT1S1 and LFXT1S0 control bits).
  • In case the existing MSP430F16x design uses a high-frequency crystal or resonator on LFXT1 or XT2, the appropriate frequency range must be configured in the MSP430F261x 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]