Microcontroller Sports Complementary ADCs

Jan. 31, 2012
Texas Instrument's 25MHz MSP430F6736 sports three 24-bit Sigma-Delta ADCs and a fast, 8-channel SAR ADC.

Texas Instruments MSP430 is one of the most popular 16-bit microcontrollers. Its low power and high performance make it ideal for a range of applications including meter reading. The 25MHz MSP430F6736 (Fig. 1) targets this space although its mix of analog-to-digital converters (ADC) make it applicable to other applications as well.

The MSP30F6736 handles not only sensing chores but also display chores as well. In fact, it is designed to work with large LCD displays with many segments. This type of display is necessary in many regions where more complex characters are required.

Fig. 1: The 25MHz MSP430F6736 includes a regular ADC plus a Sigma-Delta ADC.

The chip has a 10-bit, 8-channel, 200 Ksample/s, successive-approximation-register (SAR) ADC. Six channels are external while two are internal including temperature sensor support. A SAR ADC is faster than the Sigma-Delta ADCs.

There also has three 24-bit, Sigma-Delta ADCs. The ADC runs off a 1 MHz clock. The inputs have programmable gain amplifiers. These ADCs meets class 0.1 meters and exceeds IEC62053/ANSI C12.20 requirements.

The 24-bit ADCs are normally used for meter reading chores. Having three 24-bit ADCs allows simultaneous conversion. A muxed approach would require sequential readings.

The microcontroller family supports up to 128 Kbytes of flash program memory and 8 Kbytes of SRAM. There is a 32-bit hardware multiplier and a CRC16 accelerator.

Other peripherals include:

  • 320 segment LCD drive with 8-mux mode support
  • Three Enhanced Universal Serial Communication Interfaces (USCI) with IrDA support
  • Three Enhanced Universal Serial Communication Interfaces (USCI) with I2C support
  • Three 16-bit timers. Each has two capture/compare registers
  • One 16-bit timer with three capture/compare registers
  • 3 DMA channels
  • Password-protected real time clock

The USCI interfaces with IrDA support also have auto-baudrate detection. The USCI with I2C support can handle multi-slave addresses. All can handle SPI interfaces.

The chip also has a password-protected real-time clock with crystal offset calibration and temperature compensation. This is paired with data that would be acquired using the Sigma-Delta ADCs to prevent corruption or aliasing of information.

The chip has a range of low power modes. A separate battery backup supply handles the low frequency oscillator, real time clock and backup memory (4 words).

The Single-phase Meter EVM evaluation module (Fig. 2) provides an easy way to check out the MSP430F6736 in a meter reading environment. The EVM has inputs for voltage and current. The third input is for anti-tampering. There is an on-board LCD display as well.

Fig. 2: The Single-phase Meter EVM provides an easy way to check out the MSP430F6736 in a meter reading environment.

Pricing starts under $2. The chip comes in 80- and 100-pin LQFP packages.

About the Author

William G. Wong | Senior Content Director - Electronic Design and Microwaves & RF

I am Editor of Electronic Design focusing on embedded, software, and systems. As Senior Content Director, I also manage Microwaves & RF and I work with a great team of editors to provide engineers, programmers, developers and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

You can send press releases for new products for possible coverage on the website. I am also interested in receiving contributed articles for publishing on our website. Use our template and send to me along with a signed release form. 

Check out my blog, AltEmbedded on Electronic Design, as well as his latest articles on this site that are listed below. 

You can visit my social media via these links:

I earned a Bachelor of Electrical Engineering at the Georgia Institute of Technology and a Masters in Computer Science from Rutgers University. I still do a bit of programming using everything from C and C++ to Rust and Ada/SPARK. I do a bit of PHP programming for Drupal websites. I have posted a few Drupal modules.  

I still get a hand on software and electronic hardware. Some of this can be found on our Kit Close-Up video series. You can also see me on many of our TechXchange Talk videos. I am interested in a range of projects from robotics to artificial intelligence. 

Sponsored Recommendations

Comments

To join the conversation, and become an exclusive member of Electronic Design, create an account today!