ECEN3000/3360 - Digital Design Lab

Lab 1: Introduction to the LPCXpresso Code Red IDE and the Arm Cortex M0

2 lab periods

This lab assignment is to get you familiar with the development tools you'll be using this semester. This is the LPCXpresso LPC1114 development board with the Arm Cortex M0 32-bit microprocessor:

The LPCXpresso Development
Board
Figure 1. The LPCXpresso LPC1114 board.

Introduction

The goal of this laboratory exercise is to have your very first embedded software project successfully run on real embedded hardware. To avoid watering down the experience, we will be starting from scratch, and doing all of the work by ourselves. This means that to begin, we must install software! This includes the integrated development environments (IDEs), software development kits (SDKs), and reference source code. After it all works together, we'll change some code to get an effect we like. If we can do that, then we have set a foundation for making an embedded device control or do anything we would like it to do!

Part 1 (Install Code Red)

Download and install Code Red, LPCXpresso's Eclipse-based IDE on either a lab machine's h: drive, or on your personal laptop (since you will be most likely be needing outside of classroom time to work with this IDE, we highly encourage you to install Code Red on your own laptop). You will need to register an account in order to do so, please use any email address for the registration that you wish. For groups of two students, both will need to create their own accounts.
Please read and follow LPCXpresso's tutorial for the above procedure (doing so will speed your progress considerably).

Part 2 (The "Blinky" example)

Download the NXP-provided Arm Cortex M0 example projects and copy into the workspace directory for your installation of Code Red. Written in the C language, these provide you with great starting points for how to use of many of the M0's peripheral subsystems in your own custom projects.
Launch Code Red and build the "Blinky" example project by hi-lighting it first and then going to Project->Build Project.
After a successful build, you are now ready to run the Blinky project on the board itself. With the Blinky project still hi-lighted and the LPCXpresso board connected, go to the button on the top toolbar that is patterned after a green bug (looks like a beetle) and press it. Once the code is loaded on the board, verify it works by going to Run->Resume, which will release the code to run (after loading, the code execution is paused by default under debug mode). If successful, an LED on the board will begin blinking on and off.

Part 3 (Custom "Blinky" example)

Now that you have blinky running, let's play with it and change it to our own liking.
Read through the code provided in the Blinky project. The code you are interested in will be in the following folders: \src, \config, and \driver.
Modify the proper portions of the code such that you produce a change in both the frequency and duty cycle of the blinking LED. Don't make the frequency so fast that the TAs can no longer see discrete blinking! (Note: The human eye cannot distinguish faster than about 24-30 Hz).

Part 4 (Linking together the ADC (input) and GPIO (output) peripherals)

For this portion of the lab, you will complete a data flow beginning from an analog ADC port on the LPCXpresso board, and ending with the digital I/O pin on the GPIO port. We will apply a sine wave generated by the Agilent Function Generator in your work area. Our intended end result should be as follows. The LED should be ON when the voltage applied to the AD0 pin is greater than Vcc/2, and the LED should be OFF when the voltage is less than Vcc/2. Lastly, display the current frequency in the debug_print window, you will probably need to use a timer.
We will begin by using the "adc" example project from the example projects zip file that you have already downloaded and installed in Part 2 of this lab as our base. We have modified the main c file, which is available for you here. Download and replace the current c file in the adc example project with this one.
Next, we will need to modify some of the project settings to allow the compiler to find the necessary control drivers for to operate the GPIO pin that drives the LED (these files are omitted from consideration to reduce the size of the resulting code--code space is a critical resource in an embedded system!). For this, first add the following line of code somewhere in the /config/driver_config.h file. This satifies some of the preprocessor directive checks in the GPIO driver source files found in /driver/gpio.c and /driver/gpio.h (have a look and you can see for yourself).

#define CONFIG_ENABLE_DRIVER_GPIO 1

Next, we need to tell the compiler not to ignore these new GPIO driver files, which previously went unused in the adc example (conversely, in the LED 'blinky' project you are already familiar with, the adc driver files are similarly disabled). For this, right-click on the adc project and select properties, then follow the below Figure 2 to complete the process.
Now compile the project to make sure there aren't any errors ("Build 'adc' project [Debug]") in the Quick Start menu.

Figure 2. The gpio.c, gpio.h filter removal procedure (click to enlarge).

Configure the function generator using the below parameters to start with.

```
Wave Type:	Sine
```
```
Frequency:	1.0 Hz
```
```
Voltage offset:	1.0 V
```
```
Voltage P2P:	1.0 Vp2p
```

Using the supplied probes (next time you will need to supply your own that you hopefully still have in your ECEN-1400 kit), attach the ground side to the board's ground, and the probe side to the AD0 pin (wire will be supplied to make the ground connection easier, but you may still have to hold them in place).
Write the code in the modded_adc_main.c file needed to light the LED when the voltage is greater than Vcc/2.
Write code that can infer the frequency of any sinusoidal signal with a 1 V offset and 1 Vp2p setting. Print the frequency in real-time to the screen using debug_printf. Hint: you may need to use a timer for this.