SLAA486B January   2011  – June 2019 MSP430G2452

 

  1.   EKG-Based Heart-Rate Monitor Implementation Using the MSP430G2xx LaunchPad™ Development Kit
    1.     Trademarks
    2. 1 Introduction
    3. 2 Hardware Description
      1. 2.1 Hand Detection Circuit
      2. 2.2 Analog Front End (AFE)
      3. 2.3 Pin Functionality Mapping on the LaunchPad Kit
      4. 2.4 eZ430 RF Target Header
      5. 2.5 Power Supply Setup
    4. 3 Software
    5. 4 References
  2.   A Amplifier Options
    1.     A.1 Instrumentation Amplifier Options
    2.     A.2 Operational Amplifier Options
  3.   B Wired USB Demo With Back-Channel UART
  4.   C Wireless UART Demo With the eZ430 RF Target Board
  5.   D Hardware Schematic Diagrams
  6.   Revision History

C Wireless UART Demo With the eZ430 RF Target Board

The heart-rate monitor hardware has a six-pin eZ430 connector to which an RF target board can be connected, allowing heart-rate data to be transmitted wirelessly to another RF target board connected to a PC (access point). This configuration serves as an alternative to the back-channel UART-over-USB cable and can be used with a 3-V CR2032 coin cell battery or two AA or AAA batteries.

An example of the RF target board is the eZ430-RF2500 Development Tool Kit from Texas Instruments, which comes with an eZ430 emulator for programming and debugging the RF target board. The RF target contains the MSP430F2274 microcontroller linked to the transceiver chip, CC2500, for 2.4-GHz operation. The MSP430F2274 is programmed with the Spy-Bi-Wire (2-wire JTAG) protocol. For more details on the hardware specifications, see the eZ430-RF2500 Development Tool User’s Guide.

RF target boards with the same form factor and pinout, but different frequency ranges, are available from vendors such as Anaren [6] and Amber Wireless [7]. Table 6 shows the options.

Table 6. eZ430 RF Target Boards

Manufacturer Part Number Transceiver Chip Frequency
Texas Instruments eZ430-RF2500 CC2500 2.4 GHz
Anaren A2500R24A-EZ4 CC2500 2.4 GHz
Anaren A1101R09A-EZ4 CC1101 900 MHz
Amber Wireless AMB8423 CC1101 868 MHz

The software for programming the RF target boards and demonstrating wireless capability is provided in the zip file available for download along with this application report. The source code is written in C and project files are provided for both IAR Embedded Workbench IDE v5.10 and Code Composer Studio IDE v4.2.1. The software is based on the wireless sensor demo using the eZ430-RF2500 and uses the two RF target boards supplied with the tool kit [8].

NOTE

If using the IAR Embedded Workbench Full Version, the existing project settings will not work properly. Go to Project Options → Linker → Extra Options and uncheck the Use command line options -- ks_version. This extra option is required to overcome the 4KB code size limitation of the Kickstart version only.

One RF target board serves as the end point and the other serves as the access point. The end-point target board (connected to the hardware through the 6-pin connector, as previously mentioned) receives data through UART (9600 baud) and transmits it using the SimpliciTI protocol to the access point. When not receiving bytes from the UART, the RF target turns off the antenna/transceiver and goes into LPM3 to prevent battery drain. The access point target board (connected to the eZ430 emulator plugged into the USB port of a PC) receives data using the SimpliciTI protocol from the end point. It then outputs that data through the backchannel UART-over-USB, and the data can be displayed on a HyperTerminal on the PC at the rate of 9600 baud (see Section B).

To compile the source code files for the RF target boards with either CC2500 or CC1101, two project files have been provided with predefined settings and are named to reflect the transceiver being used. Details on compiling the project, function call descriptions, and setting up the UART and HyperTerminal can be found in the reference documents [4] and [7]. The zip files associated with these application reports contain the COM port drivers essential for the eZ430 emulator to function as the MSP430 application UART.