SLAA361A July   2007  – August 2018 MSP430F169 , MSP430F169 , MSP430FG4618 , MSP430FG4618

 

  1.   Speech and Sound Compression and Decompression With MSP430™ MCUs
    1.     Trademarks
    2. 1 Introduction
    3. 2 Compression and Decompression Algorithms
      1. 2.1 Differential Pulse Code Modulation (DPCM)
      2. 2.2 Adaptive Differential Pulse Code Modulation (ADPCM)
    4. 3 Signal Chain on Chip in MSP430 MCUs
      1. 3.1 MSP430F169 Signal-Chain-on-Chip Solution
      2. 3.2 MSP430FG4618 Signal-Chain-on-Chip Solution
    5. 4 Performance on the MSP430 MCUs
      1. 4.1 Using the Associated Code
    6. 5 References
  2.   Revision History

3.2 MSP430FG4618 Signal-Chain-on-Chip Solution

Another signal-chain-on-chip solution is possible with an MSP430FG4618. While the MSP430F169 has 60KB of integrated flash memory, the MSP430FG4618 has 116KB of flash memory. Another advantage of the MSP430FG4618 is the integrated operational amplifier module. These operational amplifiers can be used to amplify the microphone input and the analog output of the DAC. Figure 5 shows the signal chain of the MSP430FG4618 solution. This is the configuration of the MSP430FG4618/F2013 Experimenter Board. This evaluation board can be used with the associated code example.

signal-chain-on-chip-solution-using-msp430fg4618.gifFigure 5. Signal-Chain-on-Chip Solution Using MSP430FG4618

The output signal of the microphone is small and must be amplified. The MSP430 operational amplifiers can be used in different operating modes. Using the amplifier in PGA mode allows a maximum amplification of 15, which is not enough for the microphone amplifier. Additional gain is provided using external components, and operational amplifier OA0 in Figure 5 is used in general-purpose amplifier mode. There are eight performance settings for the amplifiers to allow performance (gain-bandwidth product and slew rate) to be traded with current consumption. The example code uses high-performance mode (fast mode) for all amplifiers (OA0, OA1, and OA2).

For more information about the operational amplifier, refer to the MSP430FG4618/F2013 Experimenter Board User's Guide.

The universal serial communication interface (USCI) could be used to store the audio data in an external flash memory. The connection to the external memory could be done either through an I2C bus or and SPI bus.