SLAA126B April   2001  – September 2018 MSP430F149 , MSP430F149 , TLC3544 , TLC3544 , TLC3548 , TLC3548

 

  1.   Interfacing the TLC3544 or TLC3548 ADC to the MSP430F149 MCU
    1.     Trademarks
    2. 1 Introduction
    3. 2 TLC3544/48 Evaluation Module
    4. 3 Serial Interface
      1. 3.1 Chip Select (CS)
      2. 3.2 Serial Data Input (SDI)
      3. 3.3 Serial Data Output Pin (SDO)
      4. 3.4 Serial Clock Pin (SCLK)
    5. 4 Control and I/O Pins
      1. 4.1 Conversion Start (CSTART)
      2. 4.2 Frame Sync (FS)
      3. 4.3 End of Conversion/Interrupt (EOC/INT)
      4. 4.4 Device Pinout
    6. 5 ADC Initialization and Operation
      1. 5.1 Initializing the ADC
      2. 5.2 Operating the ADC
      3. 5.3 EOC or INT
    7. 6 MSPF149 Code Example
    8. 7 References

3.2 Serial Data Input (SDI)

The serial data input to the ADC consists of a 16-bit word presented MSB first. The first 4 MSBs are decoded as a one-of-four bit command. The Configure Write command (1010b or 0xA) lets the user enable various operating modes by setting or clearing bits of the internal configuration registers. When initializing the ADC after power up, two write cycles are recommended to ensure correct programming. The first write cycle should contain the CW command, followed by zeros (0xA000h). The second write cycle can contain any valid configuration option as defined in the device datasheet. Input data is shifted into the device on the rising edge of SCLK.

During normal sample-and-convert cycles, the first 4 MSBs are responsible for channel selection and the selection of various test and FIFO read modes. The remaining 12 bits are normally zeros and are ignored by the ADC.