Nuts & Volts - March 2006

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■ BY PETER BEST

MORE FUN WITH FREESCALE’S

MICROCONTROLLERS

WELCOME BACK! Hopefully you’ve visited freescale.com, gotten yourself a copy of the free Freescale Semiconductor CodeWarrior Development Studio for HC08 v5.0., and you’ve built up your own MC68HC908MR16 MCU module.

All of the MC68HC908MR16 groundwork was done in the previous installment of Design Cycle, and we’ve got plenty of new MC68HC908MR16 stuff to cover this time around. So, be sure to download all of the MC68HC908MR16 C project files I’ve provided so you can follow along live and in real-time with the text and new MC68HC908MR16 projects I’m about to present. I’ll stop

flapping my jaws so we can get to work. Let’s begin by bringing up the MC68HC908MR16’s RS-232 serial port.

CODING AND ACTIVATING THE MC68HC908MR16 RS-232 PORT

Before we begin, I would like to

point out that when you see numbers like “0x12345” in this text, the 0x denotes hexadecimal representation. A 0b preceding a string of 1s (ones) and 0s (zeros) denotes a binary representation of the number in the spotlight. An “x” inside a binary or hex number string represents a “don’t care.” As you’ll see, I will use an “x” as a place holder when I’m highlighting certain bits in a binary number or set of hex characters.

You’ll also want to go ahead and download all of the MC68HC908MR16 project files, as I’ll be referencing them as we go along. You can get them from the Nuts & Volts website (www. nutsvolts.com) or from the EDTP Electronics website ( www.edtp.com).

■ PHOTO 1. The Target CPU window is very interesting. I recommend that you click around on its contents to see where you are taken. The Bean Drill consists of choosing a Bean using the Bean Selector, adding the chosen Bean to the project, and configuring the Bean with the Bean Inspector.