August 13th, 2009

Baudrate Converter

Baudrate Converter

A great tool for microcontroller hacking activities you might want to take on in the future is the Baudrate Converter, a device that automatically detects the baud rate of an MCU-based device you wish to hack. Using this method makes things a lot easier, so you don’t have to detect the actual baud rate using the PC or an oscilloscope – it saves a lot of time and energy and it’s also pretty simple to make.

The usual serial transmission has the Tx line on ‘high’ when idle and a single byte starts with a ‘low’ value (the startbit) and ends with a ‘high’ value (the stopbit). The idea is that, based on a few characters, the device measures the times the signal is ‘low’ and sorts them lowest to highest, detecting the real bit-time.

The baud rate converter uses the ATtiny2313 microcontroller from Atmel and the FT232 USB UART chip from FTDI. The latter supplies the power for the ATtiny. The converter has no capacitors for the crystal and runs at 20MHz using a 3.3V voltage, but it seems to be working nonetheless. The software that makes everything work is written in C and uses the 16-bit timer of the ATtiny extensively. After you connect the unknown serial port and send a few characters via a terminal-emulator, the device will detect the baud rate and the transmission of the bytes will be done accordingly, using the appropriate baud rate. If errors are detected, the converter will repeat the autobauding process.

The device has a detection range from 110 to 115200 and can help a great deal if you encounter baud rate conversion difficulties. The source code is available for released under GPLv3 license and is available for download in the link below (a .hex file is also available).

Baudrate Converter: [Link]

October 1st, 2008

LED Pharmacy Cross

This article is part of the PCB Giveaway program that we have running here at Youritronics. Morgoth will get a free pcb manufactured by BKRtech for submitting this project. If you’re interested in participating, read more on the program page.

These days most pharmacies use LED pharmacy crosses posted at their entrance to let people know there is a pharmacy there. The reasons are obvious, they look cool&hi-tech, they can be seen from distance and they can be customized really easy (well, easy customizing pretty much depends on how the manufacturer approaches things).

If you try to search the web about schematics or example codes for this kind of circuit you wont find any, and again i think the reason is obvious, the crosses are quite expensive and so is the profit for the manufacturer. So nobody is gonna post schematics for such a project, unless you’re a hobbyist and you’re having fun with electronics.

The project consists of one ATmega64, three ULN2003 and five 57 LED matrix from Kingbright(TA20-11EWA). I had the idea to build something like this but so far i haven’t had the time nor the knowledge to get it done. So i asked Morgoth if he would like to participate in the project. I sent him the LED’s, the drivers and the PCB and he started working. As you can see not many parts are involved , but the secret lies in the microcontroller, it’s the programming that does the job.


In the next pictures you can see the microcontroller board with the ULN2003 darlington arrays:

LED Pharmacy CrossLED Pharmacy Cross

The circuit was designed to receive messages trough serial interface from a computer and than display them. Morgoth also designed a custom terminal for windows which provides easy access to the display.

In this test phase a serial interface by wire was used to transmit data between the terminal and the ATmega64, but a wireless or bluetooth module could be integrated with no problem.

Also as a note, the LED’s don’t light up really bright, for that to happen you need to use drivers on the positive rail. This also applies if you’re planning to take the project to another level and use bigger LED’s

And now, watch some videos with the LED Pharmacy Cross beeing controlled from the computer:

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Data gloves with miniaturized USB controlling device

This is the reconstruction of a “Fakespace GL-8001” device with fully compatible serial interface via USB. This device fits into a very small SubD adapter housing, consumes low power (max. 20 mA), supports USB standby, may support a USB remote wakeup feature later, is much faster in responsiveness than the GL-8001, and the electronic components are fairly cheap, lower than 5 €.

Data gloves with miniaturized USB controlling device: [Link]

Serial interfacing LCD with PIC Microcontroller

Parallel interfacing LCD with MCU  needs at least 6 I/O pins (4 bit mode) and maximun 11 I/O pins (8 bit mode). The I/O pin’s can be cut down to 3 pin by serial interfacing using shift registers. There are a few shift registers that can be used such as 74HC164, 74HC595, CD4094 and other compatible 8 bit shift register. Before you attempt to do serial interfacing, it helps to get familiar with parallel interfacing, you can find many reference from internet.

Serial interfacing LCD with PIC Microcontroller: [Link][Via]

 UIR - Universal Infrared Receiver Board Assembled

And here is another infrared receiver, although its name says its universal that doesn’t mean the other Infrared Receivers aren’t. The project page first presents a MCU version of the receiver based on several types of PIC’s and than the symplified version without MCU, the one i also wrote about here. The goal is the same as for the other infrared receivers, to control your computer with any remote controller you have (TV, VCR, CD or Stereo).

UIR – Universal Infrared Receiver: [Link][Via]

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