SLAA705A July   2016  – November 2019 MSP430FR2310 , MSP430FR2311

 

  1.   How to Use the Smart Analog Combo and Transimpedance Amplifier on MSP430FR2311
    1.     Trademarks
    2. 1 Introduction
    3. 2 Configuration of the Integrated Operational Amplifiers
      1. 2.1 Configuration of SAC_OA
        1.       Example 1. Code Example for Configuring SAC_OA
      2. 2.2 Configuration of TIA
        1.       Example 2. Code Example for Configuring TIA
    4. 3 Application Examples
      1. 3.1 SAC_OA as a Transimpedance Amplifier
      2. 3.2 TIA Module as a Transimpedance Amplifier
      3. 3.3 A Current Sensing System Demo
    5. 4 References
  2.   Revision History

2.2 Configuration of TIA

Figure 5 shows the block diagram of the TIA module. The black squares are the control bits in the TRICTL register. In addition to an external pin, the output of TIA is internally connected to inputs of the eCOMP, ADC, and SAC_OA modules for further processing. The control registers of those modules must be configured to use this signal as input.

fig05_TIA_Block_Diagram.gifFigure 5. TIA Block Diagram

To enable TIA as a general-purpose operational amplifier, the TRIEN bit must be set in the TRICTL register. Configure the TRIPM bit to select high-speed or low-speed mode. A value of 0x01 must be written to the TRICTL register to enable TIA as a general-purpose operational amplifier in low-speed mode. To support faster slew rate, the high-speed mode can be set by writing a value of 0x3 to the TRICTL register. The high-speed mode consumes more power than the low-speed mode. Figure 6 shows the definition of the TRICTL register.

15 14 13 12 11 10 9 8
Reserved
r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0
7 6 5 4 3 2 1 0
TRIPSEL Reserved TRIPM TRIEN
rw-(0) rw-(0) r-0 r-0 r-0 r-(0) rw-(0) rw-(0)
Figure 6. TRICTL Register (Address 0x0F00)

The GPIO port control register P1SEL0 and P1SEL1 must be configured to enable the TIA function on the external pins. Bits 5, 6, and 7 must be set in both P1SEL0 and P1SEL1 registers to enable the TIA function on the external I/O pins.

As an example, the code sequence in Example 2 can be used to set up TIA in low-speed mode with MSPWare driverlib APIs.