Digital Interface Design and Application

7Application Case Study Examples

This chapter will provide well documented case studies to illustrate the concepts described in earlier chapters and explain some useful concepts in C to process complex input data formats. Although these applications are based on the STM32F4 Discovery platform, many of the considerations discussed apply whatever platform is envisaged for a final product. So these examples should provide a useful resource for implementations on future products and applications. The particular applications that will be considered here include a Magnetic Compass module, an MSF time receiver and a simple GPS (Global Positioning System) navigator.

7.1 An Open-Loop Digital Compass

In this application a digital compass in the form of a Freescale Semiconductor MAG3110 Digital Magnetometer [1] is employed. A small module containing this sensor SEN-12670 is available from Sparkfun Electronics [2]. The MAG3110 sensor is actually a three-axis magnetometer and uses an I2C interface to control and access the three magnetic field sensors, which are mounted mutually at right angles to each other. Several suitable interface modules are available on the STM32F4 as there are no conflicting requirements but the I2C2 module has been chosen in this case so the circuit arrangement is as shown in Figure 7.1.

Figure 7.1 The compass interface

7.1.1 Program Design

The program should ...