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

3.6 Beware of Reserved Bits!

The F23x/F24x MCUs feature a range of upgraded peripherals as compared to the F13x/F14x MCUs, such as the BCS+ and the Comparator+. This added functionality is partially achieved through the use of bits that were previously reserved on the corresponding F1xx peripheral. Newer generation MSP430 MCUs such as the F23x/F24x make use of these bits to implement additional functionality. If left in the default state, the peripheral usually behaves the same as its F1xx counterpart. However care must be taken to not unintentionally switch some of these bits, which can be caused by migrated F13x/F14x firmware. For example, consider the following comparison of CACTL2 control register of Comparator_A and Comparator_A+.

Figure 1. CACTL2 Bit Description, F1xx Devices
7 6 5 4 3 2 1 0
Unused P2CA1 P2CA0 CAF CAOUT
rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) r-(0)
Figure 2. CACTL2 Bit Description, F2xx Devices
7 6 5 4 3 2 1 0
CASHORT P2CA4 P2CA3 P2CA2 P2CA1 P2CA0 CAF CAOUT
rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) rw-(0) r-(0)

When firmware that uses the comparator module sets bit 7 and runs fine on an F14x is executed on an F24x device, the comparator inputs are internally shorted together.