9 of 208
ZBasic Language Reference 1 ZX Microcontroller Family The ZBasic Language and ZX Series Microcontrollers Chapter 1 - Introduction The purpose of this manual is to describe the elements of the ZBasic language and the ZX- series microcontrollers for those who have, at a minimum, a rudimentary knowledge of programming concepts and an understanding of basic electronics. It is not intended to teach programming skills nor electronics. There are many texts available for that purpose. The ZBasic programming language will be familiar to anyone who has used Microsoft’s Visual Basic language or NetMedia’s BasicX language. ZBasic was designed to achieve a high level of compatibility with these languages but it also incorporates some additional capabilities to improve its utility in the microcontroller environment. Even if you aren’t familiar with either of these two particular dialects of the Basic language, if you have used another fairly modern dialect you will find many familiar elements. In contrast, ZBasic is quite different from archaic dialects of Basic like the PBasic language developed by Parallax for use on the Basic Stamp series of microcontrollers. Even so, moving from PBasic to ZBasic should be a relatively easy and rewarding experience. ZBasic incorporates the modern block structured programming elements that help make programs easier to write, easier to maintain and more reliable. Moreover, it provides a good range of data types allowing efficient representation of the data items you need in your application. Beyond that, it has facilities to implement multi-tasking systems, allowing complex problems to be solved more easily. All ZBasic programs comprise, at a minimum, one subroutine. That one required subroutine must be named Main() and it must be defined as taking no parameters. Additionally, the Main() subroutine must have “public” visibility as opposed to being private to a particular module. The minimal ZBasic program is shown below, in its entirety. ' the minimal program Sub Main() End Sub This do-nothing program illustrates several points. First is the structure of comments as illustrated on the first line of the program. A comment consists of an apostrophe (sometimes called a single quote mark) and all characters following it all the way to the end of the line. It is not necessary for a comment to be on a line by itself. Characters occurring before the apostrophe are processed as if the comment portion of the line weren’t present. The second point illustrated by the program above is the manner in which subroutines are defined. A subroutine definition begins with the keyword Sub. That is followed by at least one space or tab character and then the name of the subroutine. Following the subroutine name is the parameter list, details of which are discussed later in this document. The parameter list is always enclosed in a pair of parentheses which must be present even if there are no parameters as is the case above. All of the statements, if any, between the Sub line and the End Sub line constitute the body of the subroutine. Here is another program, intended for the ZX-24, that is a bit more complicated. Const redLED as Byte = 25 ' define the pin for the red LED Const grnLED as Byte = 26 ' define the pin for the green LED Sub Main() ' configure the pins to be outputs, LEDs off Call PutPin(redLed, zxOutputHigh) Call PutPin(grnLed, zxOutputHigh)