barcode reader application in asp.net PIC Micro in Software

Maker QR Code ISO/IEC18004 in Software PIC Micro

PIC Micro
Decode QR Code In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
QR Code Drawer In None
Using Barcode encoder for Software Control to generate, create QR-Code image in Software applications.
RA0 RA1 RA2
Read QR In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Create QR In C#
Using Barcode maker for .NET framework Control to generate, create QR Code JIS X 0510 image in .NET framework applications.
_RD _WR1 _WR2
Make Denso QR Bar Code In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Generate QR Code 2d Barcode In VS .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create Denso QR Bar Code image in Visual Studio .NET applications.
Input Device Eight Input Bits Output Device 1
Painting QR Code In Visual Basic .NET
Using Barcode generation for .NET framework Control to generate, create QR image in .NET applications.
Bar Code Drawer In None
Using Barcode encoder for Software Control to generate, create barcode image in Software applications.
PORTB
Generate Code 128B In None
Using Barcode creation for Software Control to generate, create Code-128 image in Software applications.
Making Data Matrix ECC200 In None
Using Barcode encoder for Software Control to generate, create ECC200 image in Software applications.
Eight Output Bits Output Device 2 Eight Output Bits
Create GS1-128 In None
Using Barcode creator for Software Control to generate, create UCC.EAN - 128 image in Software applications.
Creating Universal Product Code Version A In None
Using Barcode drawer for Software Control to generate, create Universal Product Code version A image in Software applications.
Figure 15.7 A processor bus like parallel port can be implemented using the I/O pins of the PIC microcontroller.
Encoding MSI Plessey In None
Using Barcode printer for Software Control to generate, create MSI Plessey image in Software applications.
Barcode Maker In Objective-C
Using Barcode generator for iPhone Control to generate, create bar code image in iPhone applications.
INTERFACING TO EXTERNAL DEVICES
Painting Code 128B In Java
Using Barcode generation for BIRT reports Control to generate, create Code 128C image in BIRT reports applications.
Making Data Matrix ECC200 In None
Using Barcode drawer for Font Control to generate, create Data Matrix 2d barcode image in Font applications.
and use the I/O pins directly, but it is much more cost-effective to use an 18-pin PIC microcontroller (such as the PIC16F84) and a tristate output buffer and two 8-bit registers. The gure assumes that data is clocked in or out with negative active signal pulses. With this circuit, RA0 RA2 would be set for output and initialized to 4 (high voltage) driven out. To read the 8 data bits from PORTB, the following code could be used:
Bar Code Creator In None
Using Barcode creator for Microsoft Excel Control to generate, create bar code image in Excel applications.
Scanning Bar Code In C#
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET framework applications.
bsf movlw movwf bcf bcf call movf bsf STATUS, RPO 0x0FF TRISB ^ 0X080 STATUS, RPO PORTA, 0 Dlay PORT B, w PORT A, 0 ; Put PORTB into Input Mode
Barcode Printer In Objective-C
Using Barcode generator for iPad Control to generate, create barcode image in iPad applications.
Encode 1D In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create Linear image in ASP.NET applications.
; Drop the _RD line ; Delay until Data Output ; Valid ; Read Data from the Port ; _RD = 1 (disable _RD ; Line)
Writing data out requires similar code:
bsf clrf bcf bcf movwf call bsf STATUS, RPO TRIS B ^ 0X080 STATUS, RPO PORTA, 1 PORTB Dlay PORTA
; ; ; ; ;
PORTB Output Enable the _WR1 Line output the Data Wait Data Receive Valid _WR1 = 1.
COMBINING INPUT AND OUTPUT
Often, when working on applications, you will nd some situations where peripheral devices will use more than one pin for I/O. Another case would be when you are connecting two devices, one input and one output, and would like to combine them somehow so that you can reduce the number of PIC microcontroller pins required. Fewer PIC microcontroller pins means that you can use cheaper and less capable chips and avoid complex application wiring. In this section I will present you with two techniques for doing this and the rules governing their use. What I am presenting here may appear problematic at rst and asking for problems with bus contention, but they really do work and can greatly simplify your application. When interfacing the PIC microcontroller to a driver and receiver (such as a memory with a separate output and input), a resistor can be used to avoid bus contention at any of the pins, as shown in Fig. 15.8. In this situation, when the PIC microcontroller s I/O pin is driving an output, it will be driving the data in pin register regardless of the output of the data out pin. If the PIC microcontroller and data out pins are driving different logic levels, the resister will limit the current owing between the PIC microcontroller and the memory data out pin. The value received on the data in pin will be the PIC microcontroller s output.
PIC MICROCONTROLLER APPLICATION DESIGN AND HARDWARE INTERFACING
PIC Micro
I/O Device
10 K
Data Out Data In
Figure 15.8 A single PIC microcontroller pin can interface with a pair of dedicated input and output pins.
When the PIC microcontroller is receiving data from the memory, its I/O pin will be put in input mode, and the data out pin will drive its value not only to the PIC microcontroller s I/O pin but also to the data in pin. In this situation, the data in pin should not be latching any data in. To avoid this, in most cases where this circuit is combining input and output, the two input and output pins are on the same device, and the data mode is controlled by the PIC microcontroller to prevent invalid data from being input into the device. This is an important point because it de nes how this trick should be used. The I/O pins to which the PIC microcontroller is connected to must be mutually exclusive and can never be transmitting data at the same time. A common use for this method of connection of data in and data out pins is SPI memories, which have separate data input and output pins. The second trick is to have button input along with an external device receiver. As shown in Fig. 15.9, a button can be put on the same net as an input device and the PIC microcontroller pin that drives it. When the button is open or closed, the PIC microcontroller can drive data to the input device; the 100- and 10-k resisters will limit
Copyright © OnBarcode.com . All rights reserved.