CSE466-02au Lab Assignment 2

Objectives

• binary to hexadecimal 7-segment conversion
• how to wire a circuit on the breadboard in the design-kit
• how to program a timer interrupt
• how to debounce a switch in software

Background

• How to use the tools in the design kit.
• Driving LEDs and Ohm's law.
• Brief introduction to AVR Programming.
• In the AVR/avrgcc/gcctest/ directories, there are interrupt programming examples
• Schematic with pin connections for Lab 2.
• Datasheets
  • RS-232 Transceiver.
  • 7-segment display.
  • ATmega16 processor.

Tasks

1. Wire the circuit in the schematic on your breadboard. Verify with a multimeter that there are no shorts between power and ground, and that power and ground are actually hooked up to the chip's pins. Have a TA check the circuit over, to make sure there are no shorts.
2. Download your C code from lab 1 to test your circuit.
3. Power off the breadboard, and wire up the seven segment display, in an order of your choosing.
4. Run your code again, to verify that all segments are connected.
5. Write a binary to hexadecimal seven-segment routine that will count from 0 to f.
6. Dump the loop delay routine, and replace it with Timer 0 (p.g. 67-77 in the course reader/ATmega16 data sheet) an interrupt to control the counting on the display. Work out what the exact timing will be [Hz or ticks per second, would be appropriate], and add it as a comment to your code (including work)
7. Write code so that pressing the stop-start button halts and resumes counting
8. Write code so that pressing the up-down button changes the direction of counting. The Decimal Point on the 7-segment display should be lit when counting upwards.

Deliverables

• Demonstrate working code to a TA. You can either do this during this lab, or during the first 1/2 hour of the next lab. We will be looking for:

• Reasonble user-interface. Ie. make sure buttons are response but not overly sensitive.
• The Decmial Point should indicate direction counted (lit when counting up). It should change state even when counting is stopped.
• Changing counting direction should work properly, Ie it can't continue counting for one number in the wrong direction.
• Counting should happen at a leisurely pace.

• Turn in your commented C code.

• Make sure you work out the timing as mentioned above