|
|
Monday, 4. February 2008
Building a 7x5 LED display
rsbohn
12:50h
I'm now working on a 7x5 LED display. I use the Atmel ATtiny2313 as a driver. I don't have 35 LEDs of any one color, so I'm building it with stripes of red, yellow, and green LED's. I've got the first column of LED's installed on the circuitboard. I could use this to build a POV device, that might be fun. The firmware used the Timer/Counter 0 as a clock. Whenever it overflows an interrupt fires. The interrupt advances the row select (r13) and as needed column select (r14). After the interrupt the main loop executes. It writes to PORTB (rows) and PORTD (columns). With the timer running /256 I can watch the LEDs cycle one by one. When I bump the rate up (/1) they are all on. I wasn't sure how to use PORTD as a column driver, but I figure I'll just keep it set for input (HI-Z state) and just toggle the individual pins to output as needed. Since they will be in a logic low state they can sink the current from the LED. Applications: I'm going to use this as the display for my biofeedback project. It will show two or three numbers, then blank for a bit and repeat. I would also like to build a clock using a 7x5 array. Maybe I should buy the next one from SparkFun.com. ... Link
Constant Current Sink
rsbohn
12:27h
ucHobby has an article on building and using a Constant Current Sink. I could sure use one of these. I have the necessary parts, I'll probably put one together soon. ... Link |
8141 days of detection
mod: 12/3/08, 5:42 AM days of detection... PMOG owner
BiographyRandall Bohn lives in Orem, Utah, USA. He works as a Software Quality Engineer. He is a big fan of the AVR line of microcontrollers. He has been in the computer industry since 1989. Randall is married and has three children. rsbohn can be reached via gmail.com. status
Youre not logged in ... Login
Amazon.com DVD Shop
Amazon.com DVD Shopmenu
search
related
calendar
recent updates
Arduino Starter Kit
MAKE Blog How-to Tuesday posted a challenge: Optimize the sketch code for a pressure sensor bar graph. Here is my second attempt: int gate[] = {10, 20, 50, 100, 200, 32767}; void setup() {DDRB = 0b00111110;} void loop() { int dval = 0; int rval = analogRead(2); for (int x = 0; rval... 12/3/08, 5:42 AM Measuring Supply Voltage
I'm running my latest handheld computer on solar power. It starts up when the sun rises and runs all day. I started wondering how I could measure the voltage coming in from the solar panel. I came up with a way to use a diode and a resistor and the... 7/29/08, 9:53 AM Ten Pin ISP adapter
I've already built a six pin ISP adapter, but my Olmex cards use the ten pin ISP. I put a header on a scrap of perf board, added an LED for the heartbeat, and then connected the ten pin cable. Actually it is a fifteen pin cable, off a joystick... 7/16/08, 10:00 PM Hello 5x7 Style
Wrote a new firmware for the 5x7 display. Now it scrolls out 'hello' over and over again. I'm running it on a solar panel, so it wakes up with the sun and runs all day long. When I built the LED matrix I put resistors on the five columns. I'm starting... 6/17/08, 12:48 PM Provo, Utah
With a walkable downtown and access to two Universities, Provo Utah is a great location. I live next door in Orem. Kipplinger: Provo: Pristine Tech Mecca (Video) (Text) 6/2/08, 10:07 AM Another release of AVRISP sketch
There is a new release of the AVRISP emulation sketch for Arduino: avrisp.02.zip. This one should work with Mega8 and Mega168. mega-isp 5/28/08, 4:48 PM Sorting Out Page Sizes
There is a new release of AVRISP Emulation for Arduino. This is an Arduino firmware that allows you to program other AVR microcontrollers. The new zip file (avrisp.01.zip) should compile on the current Arduino IDE, and I changed the comments that put the wrong labels on the SPI pins. Go ahead... 5/27/08, 11:31 AM Flash Problems
I'm building a project using the AVR ATMega8 microcontroller. Once I got the thing wired up to where I could write firmware to it I found that it was always failing. I made a .hex file full of 0x10 values (256 bytes worth) and tried uploading that to the chip.... 5/16/08, 2:56 PM William's Arduino Board
I'm building an Arduino-compatible board for William. I'm building it on the Evil Mad Scientist MegaXX8 business card. It will have four built-in LEDs and a USB interface. It will also have connectors so he can use it with a breadboard. Perhaps we can connect it to some of his... 5/15/08, 7:26 AM Cybord Signal Detector
Some digital radio signals use Frequency Shift Keying (FSK). This often has one frequency for a Mark and one for a Space. I plan to build a cybord or other chip that will decode an FSK signal, producing three different values: NO_SIGNAL, MARK, and SPACE. The signals would then go... 5/15/08, 7:20 AM destinations
|
