Beyond Logic

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Parallel Ports

Serial Ports

Device Drivers

AT Keyboard Ports

USB

CMOS Image Sensors

CMOS Digital Image Sensors & Lens
Adding vision to your projects need not be difficult. Whether its machine vision for robot control or the sampling and storage of images for security, CMOS images sensors can offer many advantages over traditional CCD sensors. This article explores some of the CMOS image sensors and lenses / lens assemblies on the market. Add Image Capture to your uCLinux Systems.

AT Keyboards

Interfacing the PC's Keyboard As seen in Poptronics, July 2000
IBM Keyboards. Not really an interesting topic, one would expect. So why would you want to interface the Keyboard? The IBM keyboard can be a cheap alternative to a keyboard on a Microprocessor development system. Or maybe you want a remote terminal, just couple it with a LCD Module. If so, then this page has all the required information to get you started.

101 AT Keyboard to ASCII Decoder using 68HC705J1A MCU (Ideal Keyboard Bios for Embedded Linux)
An interfacing example for the AT keyboard is given showing the keyboard's protocols in action. This interfacing example uses a 68HC705J1A MCU to decode an IBM AT keyboard and output the ASCII equivalent of the key pressed at 9600 BPS. Includes Direct Decimal and Hexadecimal Enter Routines. Ideal companion to a microcontroller development system or embedded system.

"Thanks for your wonderful Web page on the Qwerty keyboard protocols! I'm attaching one to an 87C51 and was at a loss for decent info. Even Circuit Cellar Ink let me down this time. I played it by your rules and it fired right up. Please keep up the great site!"

Ray Van Vynckt - Tue, 5 May 1998

Universal Serial Bus

Universal Serial Bus Hardware Options
Looks at some of the Universal Serial Bus Microcontrollers and I.C's on the market today. These include the Cypress CY7C63001A, Motorola 68HC705JB3 & 68HC705JB4, Philips PDIUSBD11, PDIUSBD12 & PDIUSBP11, National Semiconductor's USBN9602, Microchip's PIC16C745 & PIC16C765, AnchorChips EZ-USB Family with links to the USB USB-IF Developers Discussion Forum.
The Philips PDIUSBD11 USB Peripheral with I2C Serial Interface. What you need to know.
Philips has two USB devices which allows any microcontroller the ability to talk USB. However while the silicon has any features which others don't, the data sheets are a little light on content. In fact they miss some fundamental Initialisation routines needed to get the device working in the first place. This article gives a sample schematic and the answers to many questions kindly answered by two Philips Engineers.
USB Driver for the Cypress USB Starter Kit
One of the most helpful aids when first starting out in something new is examples. Cypress forgot this when they introduced their USB Starter Kit. But then for $99 U.S., you can’t expect the world. The USB Thermometer Driver and Application was developed under contract by System Solutions 72410.77@compuserve.com. The code is not freely available. What I have done is modified the WDM ISO USB driver distributed with the Windows Device Driver Kit for use with the Cypress Digital Themometer. I’ve kept it basically the same, so you can actually run the Digital Temperature Application on this driver to see that in-fact it does work!

Interfacing the PC was awarded the
PC Webopaedia Outstanding Page Award in
July 1998

Parallel Port Interfacing

Interfacing the Standard Parallel Port
Describes interfacing the Standard Parallel Port (SPP). Includes a general introduction to Parallel Ports (SPP, EPP & ECP) and their standards. Looks at reading 8 bits of data using the bi-directional port, and using other methods such as reading a nibble at a time etc. Also details the Parallel Ports interrupts. Programming examples using C are included along with a detailed description of the Parallel Port's Registers.
Interfacing Example - 16 Character x 2 Line LCD
This is the first interfacing example for the Parallel Port. This example shows connecting a 16 Character x 2 Line LCD module to the Standard Parallel Port (SPP.) Shows the use of the Parallel Port's Data and Control Ports.
Interfacing the Enhanced Parallel Port (EPP)
Interfacing the Enhanced Parallel Port is the first page, out of the Parallel Port Series which has been revised. This page, devoted entirely to the EPP port, now includes waveforms plus a more detailed description of this Port.

Interfacing the PC's Parallel Port Pages are Links²Go Key Resources
View other Parallel Port Key Resources
Interfacing the Extended Capabilities Parallel Port (ECP)
Interfacing the Extended Capabilities Parallel Port has just been revised. This page focuses on the Extended Capabilities Parallel Port (ECP), and now includes waveforms plus a more detailed description of this Port.

Parallel Port Debug Tool
The Parallel Port Debug Tool is a handy DOS utility when debugging devices connected to the Parallel Port. It gives a visual display of the three software registers used by the Standard Parallel Port. Each individual bit can be turned on or off by a simple click of the mouse.

"I want to thank you for putting your excellent tutorials on RS-232 and parallel port interfacing on the web. It was exactly what I was looking for this weekend when I needed to cobble together some quick circuitry and code to control a device from the PC serial port. Your page had all the info I needed for programming the UART and wiring things up."

Steve Haehnichen - Sun, 8 Feb 1998

Serial / RS-232 Interfacing

Interfacing the Serial Port - Parts 1 and 2
Explains the pin diagrams of the RS-232 Port and the 8250 & Compatible UARTs. Includes information on handshaking, Null Modems, DTE/DCE Speeds, flow control, types of UART's etc. The second part of this series gives details of the Serial Ports Registers for the PC (8250 to 16750 UARTs) and the Serial Port's Addresses in the PC.

Interfacing the Serial Ports - Parts 3 and 4
Starts with example programs written in C, using both the Interrupt Driven and Polling methods for the PC. Gives details of how the programs work and how they can be changed to suit your requirements, i.e. Changing addresses, FIFO Buffers, IRQ's etc. It then gives details of interfacing your own projects to the RS-232 Port using MAX-232's, CDP6402 UART's and Micro-Controllers.

Beautiful page Craig. Well explained, easy to understand.... I'm a novice and usually do not enjoy reading technical info. but your style of explaining things is great, especially when it comes to your discussion about serial ports and cables. Holding up a Foster's beer to you and putting a shrimp on the barbi ! Cheers mate!

Mark, USA - Tue, 25 May 1999

Windows Device Drivers (Windows NT/2000 and 98 WDM)

Device Driver Tools - Making your life easy
Features three Device Driver Tools for making your life easier. Writing Device Drivers? Perhaps playing with Cypress Semiconductor's USB Starter Kit? If so, the Device Driver Fiddler allows you to test DeviceIOCommand() Calls before you write your User Mode Application. . . The Windows NT Device Driver Installer prevents making and testing of your newly written drivers a chore. It loads, unloads, starts and stops Windows NT Device Drivers. The Device Driver Remover, removes all traces of your device driver.
USB Driver for the Cypress USB Starter Kit
One of the most helpful aids when first starting out in something new is examples. Cypress forgot this when they introduced their USB Starter Kit. But then for $99 U.S., you can’t expect the world. The USB Thermometer Driver and Application was developed under contract by System Solutions 72410.77@compuserve.com. The code is not freely available. What I have done is modified the WDM ISO USB driver distributed with the Windows Device Driver Kit for use with the Cypress Digital Themometer. I’ve kept it basically the same, so you can actually run the Digital Temperature Application on this driver to see that in-fact it does work!

Interfacing the PC was awarded the
StudyWeb Excellence Award
in January 1998

Assorted Documents & Programs

Ethernet & TCP/IP Interfaces
Internet and ethernet connectivity is big business these days. We look at three options, including Seiko Instrument's award winning hardware TCP/IP stack, the uCSimm Embedded Ethernet Controller running Linux and Dallas Semiconductor's TINI Embedded Ethernet Controller running JAVA.
The Concise LCD Data Sheet
The Concise LCD Data sheet, features all the required data on the HD44780 & compatible LCD Modules on one easy page. Included is the Instruction Set, Write Operation Waveforms, Timing information & the LCD Module's Pin numbering & description. Everything you need to get started. Only available in PDF (19.7Kb).
How does the Microchip ICD Work?
The PIC16F877 was the first Microchip Microcontroller to have in-built debugging capabilities. The actual silicon area used for the debug facilities is tiny compared to the major peripherals. Microchip has keep the operation of the debug facilities pretty well under raps, however it doesn’t take much reading between the lines to work out how the actual debugging facilities are implemented. Also includes details on making your own ICD.
Opinion : A look at Windows 2000
In the past month, there has been a range of articles on Windows 2000. Some good, some bad. I’ve never been one to praise Microsoft’s products, but in my view Windows 2000 seems to be the best thing since Windows 95 (Sliced Bread). Just take a look at some of the features including ICS Internet Connection Sharing, WFP Windows FIle Protection, Hibernation and Dial up Networking . .
Using Interrupts
A dedicated document exploring the use of interrupts on your PC. Includes information on the IRQ 2 to IRQ 9 Re-direction, the 8259 and compatible Programmable Interrupt Controller (PIC), Initialization Command Words (ICW's), Operation Command Words (OCW's), Interrupt Service Routines (ISR), Interrupt vectors and using interrupts under the C environment.

Premium Content and Upcoming Pages (Restricted Access)
Drafts and trial executables of upcoming pages. Restricted Access.

"I was sent to your page on serial communications by a fellow engineering student, admittedly with a certain degree of cynicism, never expecting to find what i did. It is a heartfelt relief to see something substantial on a scale such as your page for once. Its nice to see that beyond all the intellectual refuse on the internet there are yet those who take pride in what they post beneath their name. Wont take up any more of your time, just thought id let you know your hard work is definitely appreciated!"

Alguire Josh - Wed, 05 Nov 1997

Interfacing the PC . .
Awarded the Electronics 2000 5 Star Award in April 1998

Links

Universal Serial Bus
Parallel Ports
Serial / RS-232 Ports
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"I have read your web page on serial interfacing and found it extremely informative. The doc on the parallel port was presented in a way that made it the most logical and easiest to understand out of all the docs I have read on that subject."

Ryan Smith - Thu, 21 Jan 1999

The Interfacing Discussion Group

Parallel Ports

Serial Ports

Device Drivers

AT Keyboard Ports

USB