Various Circuits

One of the nicest features of the 8-bit KX8 microcontroller (manufactured by Freescale Semiconductor) is that it includes an internal clock generator (ICG). This allows the chip to run without the trouble and expense of an external crystal or canned oscillator.

Bugdozer is an autonomous mini-Sumo robot. Her main board consists of a MC68HC908GP32 microcontroller along with input/output support chips, a voltage regulator, a crystal oscillator, and the usual assortment of resistors, capacitors, and switches. All chips are socket mounted. I'm not experienced at soldering, so soldering the sockets avoided damage that could have resulted from soldering the chips directly. Also, if a chip becomes damaged in battle, it can be replaced easily.

The microcontroller is able to make about 7000 complete line-following decisions per second, which is almost 7 decisions per millimeter when the robot is going full speed. By upping the clock, unrolling loops, and removing my wireless debugging and extraneous code, I could increase the number of decisions per second.

Built using a PIC16F84, about 4 hours worth of code and a few bits on a breadboard. This was the first time I've worked with PIC's so it was a learning exercise. I started with the 'Hello World' microcontroller equivalent i.e. Blinking LED, then tried the 'Knight Rider' sequencing LEDs, and then hacked this together. The code is written and assembled using the Microchip MPLAP IDE V5.70. I only did this as an exercise to familiarise myself with PIC assembler.

This project is a combination Logic Probe and Logic Pulser. It is capable of testing all sorts of digital and microcomputer projects. You will find it extremely handy when designing a project as the golden rule is to test everything in steps and stages during the design-and-construction process. If you are not sure how a Logic Probe or Pulser works, let me explain.

The project consists of 35 LEDs arranged as a 5x7 matrix. This may not seem very impressive but you can display all sorts of effects and treat it like a "window on a large video screen." The project comes with a series of test programs to test the operation of the screen and also the surrounding components. Then we come to the experiments. They start with a simple routine to illuminate a single LED and progress to flashing a LED, running a set of LEDs up and down the screen, and then a variety of animations.

On these pages, I will introduce a control circuit for stepper motor. The software of this project is adapted to Embedded Systems(Lab13) for 2002 of Cleveland State University.

This was my first sucessful project with a PIC chip. I used a 16F84 with a 10MHz resonator with built in caps. Click here to view the source code to this project. The code is written in Hi-Tech C. Click here to download the source code to this project. File has a ".c" extension.

Here is a neat PIC project that I created using the 16F84 chip and a neat little bi-color LED from Radio Shack. The LED can be red or green depending on the bias of the diode. By using two of the PORT B pins, I can control the bias of the LED. If the LED is on PORT B, Pin 0 and Pin 1, I can set Pin 0 HIGH and Pin 1 LOW, this would make the LED light red. If Pin 0 is set LOW and Pin 1 is set HIGH, the LED will light green. PORT B has 8 pins, so I was able to connect up to 4 LEDs and have full control of them all (as seen in the schematic).

This is pretty much just a spinoff of the original LED chaser above. It's based on the PIC16F84 clocked at 10MHz. I found that many "emergency personel" were looking for simple flashers that they could mount in their vehicals. I searched around and found many different ones, but many we're very pricey ($50 - $100). This is a basic model that can be adapted to many applications. I plan to make a new version using the water-clear LED's. They are much brighter and can be seen during the day better.

Using a modified version of the last program, we can control as many servomotors as we have I/O lines on port B. In the next listing, we will control two servos in the same manner as we controlled a single servo in the previous program. The circuit is shown in figure 4 (below). The program uses two pulsewidth variables, pw1 and pw2; and two sets of routines, left1 and left2, right1 and right2; one for each motor. As you can see in the schematic, the first servo is wired as per the previous circuit.

This LCD terminal provide two modes of operation by selecting jumper J1. When J1 is open the terminal operate as a normal ascii display terminal, when J1 is closed the terminal displays the input serial data in hexadecimal format. This mode is useful for viewing raw data from the serial port output. IC U2 a PIC16F84 micro controller is used to control the operation of the terminal. Input signal is applied to connector K1. The circuit can be powered either by 9V dc adapter or by using a 9V battery. Jumper J1 select the operating mode of the terminal, J1 open for ascii terminal mode, closed for hexdecimal display mode.

I made LED flash circuit which is often used as the PIC software making practice. This circuit controls the blink of eight LEDs with the software of PIC. The blinking pattern can be changed with five switches.

On this page, I will introduce the electronic signboard with PIC16F84A. 112 LEDs are used for message display and 50 LEDs are used for around. Latch registers by CPLD are used for the display of the LEDs. So, LEDs can be brightly lit up compared with "Signboard".

On this page, I will introduce the electronic signboard with PIC16F84A. The message is displayed to flow on the left from the right. 128 LEDs are used for this board.

The JavaBot1 is a small line following robot designed to follow a black line drawn on a dry erase board. It is designed to follow very tight curves. The software still has lot's of room for improvement but works well as is. The JavaBot1 uses 2 Cirrus CS-70 servos that have been modified for full rotation and have had their controller boards removed to convert them from servos to gear motors. Servos are a common motive power for small robots due to their low cost, ready availability,

The F84 MRTC was my second design of a miniature real-time controller. This version uses PIC16F84 running with a low power X-tal 32,768Hz. The scheduler for 6-channel output was saved in EEPROM. No terminal for serial downloading of the scheduler. It's suitable for fixed scheduler job. Two AA size battery provides +3V backup for clock operation when main power has failed. Time setting at 19:00 is set only once by pressing S1 button. The 6-channel open collector output provides max. 30mA @30V load.

I finally found a very nice universal window based software designed to work with any serial programmers for PIC16F84, i.e., WPicProg16 V1.20, written by Nigel Goodwin. Build this programmer before started experimenting the forthcoming many interesting F84 projects. Some PIC programmers can be used for in circuit programing, some provide many PIC chips including eeprom, say. The F84-Programmer, however is suitable for beginners. It's so simple and cheap.

On these pages, I will introduce Remote Controller with Radio Frequency. The electric wave sending-out is controlled with the code by PIC for transmission and the code is deciphered by PIC for receiving. You can jump to the page of photographs when you click the part where the pointer become the hand.

I will introduce the constant speed controller for DC motor. It detects and controls the rotational speed of the motor. When lower than the specification speed, it increases a control electric current. When higher than the specification speed, it reduces a control electric current. It is possible to use when wanting to keep constant speed even if the load to the motor changes. With the circuit this time, I used a motor for the speed detection apart from the main unit motor. The speed can be detected in the other way, too. LEDs are lit up to confirm the control situation of the motor.