Reading and CReating Pulses in Software

Creating QR Code in Software Reading and CReating Pulses

Reading and CReating Pulses
QR Code Reader In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
QR Code ISO/IEC18004 Printer In None
Using Barcode creation for Software Control to generate, create QR Code image in Software applications.
Other complications have to do with making sure that only the responsible cog is allowed to change the pulse width value and that the variable being used to store the pulse width is not altered by any other cog.
Quick Response Code Decoder In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Draw Denso QR Bar Code In Visual C#
Using Barcode printer for .NET Control to generate, create QR-Code image in VS .NET applications.
note Because we do not know when a shared value in the VAR block might be read by one of the cogs, it has to maintain a valid value at all times. This was covered earlier in the book, but is important enough to repeat here.
QR Code 2d Barcode Generation In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Creating QR Code In .NET Framework
Using Barcode drawer for VS .NET Control to generate, create Denso QR Bar Code image in .NET framework applications.
In this discussion we are assuming that the pulse width we are interested in either does not vary at all or varies very slowly during the reading process (which is indeed the case for this particular sensor). If rapidly changing values have to be read, that is a whole other problem that we will not discuss in this book. However, you should be able to address the situation after you have successfully performed all the exercises in this book.
QR Creation In Visual Basic .NET
Using Barcode creator for .NET framework Control to generate, create Denso QR Bar Code image in VS .NET applications.
Paint Code 128 Code Set C In None
Using Barcode creator for Software Control to generate, create Code 128C image in Software applications.
Determining the Pulse Width
Encode Bar Code In None
Using Barcode maker for Software Control to generate, create barcode image in Software applications.
Make Code 39 In None
Using Barcode creator for Software Control to generate, create Code 39 image in Software applications.
In Part III of this book, we will be using the Memsic 2125 gravity sensor in an experiment, so we are interested in looking at how this sensor behaves as it is tilted. The information will be used in 27 to create an intelligent system that maintains a table in a horizontal position in the X and Y directions as the table base is tilted. We know that this sensor provides two pulse widths as its signals, so we will create the software to determine what the characteristics of these pulse widths are, one at a time. The two pieces of information of interest are the cycle time of the signal and the characteristics of the pulse within it. For most sensors, the cycle time remains constant and the pulse width varies, but this might not be the case for this sensor. At this point, we just don t know.
Generating Barcode In None
Using Barcode printer for Software Control to generate, create bar code image in Software applications.
Paint Data Matrix In None
Using Barcode maker for Software Control to generate, create ECC200 image in Software applications.
note Reading the system clock and using the result in the waitcnt instruction takes a certain amount of time in Spin (381 clock cycles to be exact). Because a minimum for two consecutive reads is needed to read a pulse width, the shortest pulse width that can be read under the best of conditions is 381 clock cycles wide. Because the clock rate is programmable, the width readable also depends on the clock speed specified in our program. We will assume a clock running at our usual 10 MHz for this experiment. If we divide 10,000,000 by 381, we get the highest frequency we can measure in this way. The value is 26,246.7 cps.
Painting 4-State Customer Barcode In None
Using Barcode maker for Software Control to generate, create USPS Intelligent Mail image in Software applications.
Barcode Encoder In None
Using Barcode drawer for Word Control to generate, create bar code image in Word applications.
To get a handle on what we are about to undertake, let s note that at 10 MHz, 381 cycles take 381/10,000,000 = 0.0000381 seconds. This equates to a signal running at 26,246.7 Hz. This is a theoretical maximum, meaning that if anything else slows our measurements down, it will get worse it cannot get better. For our purpose, the pulses that we are likely to encounter will have pulse widths that vary between about a millionth of a second and about 10 seconds. This range can
European Article Number 13 Maker In Java
Using Barcode maker for Java Control to generate, create European Article Number 13 image in Java applications.
ECC200 Generation In .NET Framework
Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications.
deteRmining the Pulse Width
Data Matrix Printer In Objective-C
Using Barcode drawer for iPad Control to generate, create DataMatrix image in iPad applications.
Scanning Code 39 Full ASCII In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
be laid out in a simple tabular format so we can see what techniques are suitable for what pulse width: 0.000001 seconds 0.00001 0.0001 0.001 0.01 0.1 1.0 10.0 1 second 10 seconds 1 millisecond 1 microsecond Too fast. Use I/O compare scheme. Close. Use I/O compare scheme. Over 0.0000381. Can use waitcnt. Can use waitcnt. Can use waitcnt. Can use waitcnt. Can use waitcnt. Can use waitcnt.
Barcode Recognizer In Visual C#
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
UPC-A Supplement 2 Generation In Objective-C
Using Barcode maker for iPhone Control to generate, create UPC A image in iPhone applications.
For extremely long intervals, the waitcnt instruction has to be used with care because the 32-bit counter overflows every 7.158 minutes (at 10 MHz) and less often at higher frequencies. The value is calculated from: 65,536 65,536/10,000,000/60 = 7.158 minutes We know from the literature provided with the device that each of the two axes on the Memsic provide a pulse width that varies with the tilt of the sensor. The signal is provided at 100 Hz. When the sensor is perfectly horizontal, the signal s duty cycle is 50%. The pulse width increases and decreases by about 25% as an axis is tilted by 90 degrees from horizontal to vertical in either direction. Being good engineers, we will verify this for ourselves by looking at the two signals with an oscilloscope. Make it a habit to look at whatever you are working with, with the many instruments you may have in your shop, to get a preliminary feel for the behavior of the device you are about to employ. The more you know about the device before you start, the greater the chances for your success in using it effectively. We now have the expertise to use more than one cog to solve a problem. In this program, we will read the pulse widths generated by a Memsic gravity sensor with one cog, display the values on our LCD with another, and output any signal we may need on a third cog. Cog 0, the main cog, will be used to display the length of the pulse (for the X or Y axis), the cycle time, and the frequency of the signal on the two lines of the LCD. Cog 1 will determine the various values and place them in appropriate variables. At the same time, we will look at the signal we are receiving with an oscilloscope so that we can relate what we are seeing to what we are reading with the Propeller chip. First, we need to read a pulse length with one cog. Let s decide that we are going to measure the high part of the signal. Although this is not always so, the high part is what we mean when we say pulse width. We can also express the pulse width as a percentage of the total cycle time when that is more appropriate.
Copyright © OnBarcode.com . All rights reserved.