July
20
2012
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This is the final article in my ATtiny2313 breadboard header series. In the previous parts we’ve looked at:
In this part, I’ll have a short review of the PCB ordering process with Olimex, and a bit how the boards turned out. Let’s get going!
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Posted by jokkebk June
18
2012
There still seems to be a lot of traffic to my V-USB tutorials, so I thought I’d write a short follow-up post on USB keyboards. I already did a USB HID mouse post earlier, so you might want to check that out to understand a bit about HID descriptors and associated V-USB settings (in short, human interface devices send a binary descriptor to PC telling what kind of “reports” they send to the host on user activities).
As a basic setup, you’ll need a working V-USB circuit with one switch and one LED attached. Here, I’m using ATtiny2313 with the LED wired to PB0 and switch to PB1. The ATtiny is using 20 MHz crystal, so if you’re following my USB tutorial series and have that circuit at hand, remember to change that frequency in usbconfig.c before trying this out. Note the cool breadboard header I have, there will be more posts about that one to follow soon!
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Posted by jokkebk 
Tagged with: ATtiny2313, breadboard, hid, hid descriptor, human interface device, keyboard, switch, tutorial, V-USB April
12
2012
Before diving right into SPI communications for my SD tutorial, I wanted to have a 3.3V development platform that could output some meaningful status information, not just light a LED if something goes wrong. In this post, I will outline the basic testing platform that will be used in the upcoming part 3 of that tutorial, and discuss a little about UART on AVR in the progress. Here’s what we’ll build:
If you want to build it yourself, you’ll need:
Posted by jokkebk February
24
2012
The reason a started my electronics hobby was that I wanted to build a chess clock. Lacking a proper LCD display, I chose to multiplex several 7-segment displays. Most sources in the net did not specify hardware at all, and those that did were driving the segments with a 74HC595 shift register and using NPN transistors to enable one common cathode display at a time. However, if you look at 74HC595 specs you’ll notice that it’s not designed to source the amount of current that is required to drive several multiplexed 7-segment displays. It might work, but no one can say for how long!
It took me a while to find a good, inexpensive and readily available alternative. I finally found it in ULN2003, which is inexpensive darlington array that can drive 500 mA from each of its pins. So I decided to write a little tutorial on 7 segment multiplexing that walks through all the needed hardware and software in detail. Here’s what we’ll build (click for a larger image):
For this tutorial I assume you know how to connect ATtiny2313 to a programmer and flash it with custom software. You’ll learn as much in IMakeProjects.com’s AVR tutorial. You’ll also need the following components:
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Posted by jokkebk February
13
2012
Since my brief journey to controlling LCD display directly with ATtiny2313 I purchased a display with Hitachi HD44780 compatible driver chip. The web is already pretty full of LCD tutorials and libraries, but most seemed to either skip details and rely on external libraries, or were just overly complex. So I decided it wouldn’t hurt to share the rather short (and functionally limited) versions I came up with.
In 8-bit mode, you will be needing 8 pins for sending or reading a whole byte of data at once, and 3 control lines: enable (EN), register select (RS), and read/write (RW). Basic procedure is to prepare all other lines, and then pulse the enable line high for a short while in which LCD reads your command (when RW is low) or writes data (when RW is high). For control messages, RS line is low, and for writing letters, RS line is high.
I started with ATtiny2313 and used the 8 pins in port B as LCD data lines, and PD4, PD5, and PD6 as RW, RS, and EN, respectively. With such a setup, working write command became:
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Posted by jokkebk February
4
2012
All right. Now that we got the basic USB code working in part 3, it’s time to wrap things up in this tutorial series. This fourth section will explain how to send data from your device to PC and also the other way around. I may later do a fifth part on how to make a USB HID device like a keyboard or mouse, so if you haven’t already, I’d recommend subscribing to the RSS feed to get updates.
If you look carefully at our command-line client code, you probably noticed that the control messages sent to toggle the led are of type USB_ENDPOINT_IN and we have a 256-byte buffer in place to receive any data the device sends. So far we have not received any data and the return value stored in nBytes has been zero. Let’s change that.
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Posted by jokkebk January
29
2012
This is the third part of my USB tutorial for ATtiny2313 and V-USB library. In the second part we got the breadboard setup more or less covered, and now is the time for actual code! This will most likely be the longest of the three parts, so let’s get started.
First, we will download the latest version V-USB library from OBdev. Head to the Downloads-section and get the latest .zip – I got vusb-20120109.zip.
Unzip the archive and copy the usbdrv subfolder to your project folder (the whole folder, not just contents). Go to the subfolder and make a copy of usbconfig-prototype.h with the name usbconfig.h. Locate the #define lines for IO port and port bits and clock rate, and update them as necessary to reflect our configuration where D+ is in PD2 and D- in PD3 and clock rate is 12 MHz:
#define USB_CFG_IOPORTNAME D #define USB_CFG_DMINUS_BIT 3 #define USB_CFG_DPLUS_BIT 2 #define USB_CFG_CLOCK_KHZ 12000
Posted by jokkebk January
25
2012
This is the second part of my USB tutorial for ATtiny2313 and V-USB library. In the first part we learned how to get 3.3V from USB to power our circuits. In this part, we will expand our setup with following parts:
Update: Some people have noted that the setup I’m using here runs ATtiny2313 at 12 MHz with only 3.3V VCC, which is outside the specified range (frequencies over 10 Mhz require 4.5V or more). I’ve never had any problems, and many others have succeeded with this setup, but if you encounter persistent problems, I suggest you to power the ATtiny2313 straight from 5V of the USB line and use zener diodes on D+ and D- lines to drop their voltage, as is done in my later tutorial with the ATtiny85 microcontroller.
This time I will not walk you through every connection. Instead, I’ll just outline the steps needed and show the pictures of end result. Here is the schematic we’re building:
January
22
2012
I wanted to build an USB device using AVR microcontrollers since I found out that it was possible. However, both the USBtiny project and the more extensive V-USB library lacked an easy-to-approach tutorial. So I decided to make one.
This first part covers the basics for making USB-powered devices, and serves as introduction for second part, which goes through simple example for using V-USB library to implement USB communication to and from ATtiny2313. Additional parts might be published later if I have the time and there’s interest.
But let’s get started. Here is what you need for this first part:
The first thing we need to do is cut the USB cable so the end that goes into computer remains, strip the other end and solder the four wires into a pin header so it’s easy to plug the cable into a breadboard. USB contains four wires which you should solder in the following order (note: not all cables conform to this so check with a multimeter!):
| Pin | Color | Function |
|---|---|---|
| 1 | Red | VCC (+5V) |
| 2 | White | D- |
| 3 | Green | D+ |
| 4 | Black | Ground (0V) |
Here you see the end result. When stripping the wire, be careful not to damage the wires and make sure the wires will not touch each other so your cable won’t short circuit your computer or USB hub!
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