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

5.1 Initializing the ADC

Initializing the ADC is a relatively straightforward task. After power up, EOC/INT is high and the data registers are set to zero. The user has the option of setting a default hardware mode, or programmed mode. Each mode requires two 16-bit initialization cycles. Data output from the power up initialization phase should be ignored. For the purpose of this application report, the initialization cycle consists of chip select being held low through two 8-bit SCLK cycles.

Hardware mode is defined by the status of the SDI pin. After power up, two consecutive initialization cycles put the device into hardware mode if the SDI pin is tied to DVDD. This loads the ADC’s configuration register with 0x0800h.

To enter the programmed mode, the host processor must write 0xA000h (WRITE CFR + 000h) to the SDI pin during the first initialization cycle, followed by a WRITE CFR + DATA command during the second.

adc-initialization-cycle.gifFigure 2. ADC Initialization Cycle