Unlocking RS232 Serial Comm On A Multimeter

November 30, 2010 by Mike Szczys 20 Comments

[Craig] cracked open a multimeter to unlock RS232 serial communications that can be used for data logging. There’s a couple of things that make this possible. First of all, the multimeter’s processor is not covered in a black epoxy blob, leaving the pins exposed for hacking. Second, the chip model is known and [Craig] was able to get his hands on the datasheet. One of the pins enables serial output when pulsed low. Touching it to V- even turns on an RS232 icon on the display, as seen above. To make this accessible without opening the case a momentary push button can be added, as well as connector for signal output, and a bit of parsing on the PC side to handle incoming data.

Interface Up To 12 Servos Using Arduino

November 24, 2010 by Mike Szczys 5 Comments

[Brian] is using an Arduino to control multiple servo motors. This is nothing new and has been happening since the earliest days of Arduino. But rather than develop a project and share it, [Brian] did a fantastic job of making the code scalable, readable, and even explained how the different parts work.

His code listens for serial commands and manipulates the motors accordingly. He wrote a Python script using pyserial which talks to the Arduino. As an example, he uses a joystick to send data for X and Y axes as well as pitch and roll. Want to know how those serial communications work? He explains that in detail. He also outlines the process of scaling up from the 4 servo demo to 12 servos on a standard Arduino. Sounds like it might be time to build your own version of a mouse-controlled Lynxmotion arm using the tools [Brian] has put together.

Communicating With An LED Matrix

November 19, 2010 by Mike Szczys 9 Comments

Most of the LED matrix posts we run delve into the hardware design. This time around [J Bremnant] used prefab modules and focused on writing code to address the display. The hardware combines two 24×16 LED boards from Sure Electronics with a Teensy 2.0 to drive the display and provide a USB connection. The firmware comes in just under 8k, leaving graphic manipulation up to a PC.

[J Bremnant’s] Python script offers a lot of flexibility when working with the display. There are three modes selectable through a terminal interface. One just tests the display and then drops into Conway’s Game of Life. The second mode lets you send commands via serial interface so it can be used as a message ticker. The final feature is frame addressing that allows graphics to be dropped into the display. See each of these featured in the video after the break.

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Android Talks Pulsewave

November 10, 2010 by Joseph Thibodeau 41 Comments

Serial communications are a mainstay of digital computing. They don’t require much physical infrastructure and they exist in variations to fit almost any application. The behaviour of serial communications lines, varying from high to low voltage in a timed pattern, is analogous to a 1-bit DAC. Using a whole DAC for serial communication would be a waste in most cases, but the [RobotsEverywhere] team found an exception which you may have encountered already.

Since the audio output of the Android is accessible and addressable, [RobotsEverywhere] wrote source code to use the left and right channels as separate serial communication lines. This circumvents the need to bust into the device and muck about with the hardware which is great if you want a no-risk hack that allows communications to an RS232 port. Any hardware on which you can write to the DAC (and control the sampling rate) is a potential target.

There are some external electronics required to convert the audio signal to TTL, but it’s not very complicated–a couple of comparators and change. You can see it in action after the break.

As a bonus, when you’re done for the day you can plug in your headphones and listen to the soothing poetry of pulse waves all night long.

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Multiple Core Propeller Speeds Up Display Addressing

October 21, 2010 by Mike Szczys 22 Comments

If you ever wondered what an eight-core Propeller processor can do for you, [Tom] found one answer. He’s using the multiple cores to individually address serial displays. He has six display modules, and each of them incorporate six 8×8 LED modules. This makes for a total of 2304 LEDs, and since they’re addressed by cascading serial data, that means 2304 bytes pushed to the display. You’re going to suffer from quite a bit of slow-down if you choose that communication method.

This is where multiple-cores come in handy. Instead of cascading data between the six modules, he assigned a different core to each. Now he can concurrently address the six displays, reducing his serial data from 2304 bits per frame down to 384 bits per frame. As you can see in the video after the break, updating the display six times as fast as before yields fantastic results.

Now what if you’re using a processor that has forty of these multi-core Propeller chips?

This does make us wonder, can’t the same thing be done on a single-core processor? An eight-bit device takes one cycle to set all eight bits on a single port. So why not just connect the six serial connections on six bits of the same port? Weigh in with your thoughts in the comments.

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Cheap And Easy SMS Via GSM For Your MCU

October 18, 2010 by Jakob Griffith 68 Comments

Non acronym version of the title: send and receive text messages via cell phone communication towers using an Arduino or other microcontroller. “We’ve been doing that for years!” you cry, well yes, technically. But [Fincham] lays it outs simply; commercial offerings are expensive and finding a cell phone that uses RS232 now a days is getting difficult, so a new way of doing the same old is necessary. The good news is USB GSM modems are readily available, cheap, and only require a few interface pins to get them talking with an Arduino. In fact, the image above is all you need.

Game Boy Printer USB Cable And Software

October 8, 2010 by Mike Szczys 19 Comments

[Furrtek] hooked up his Game Boy printer for use with a PC (translated). The two-part hack started with a cable to attach the device via USB. A Nokia interface cable was used as a base to translate the USB signals into serial, and an ATtiny45 microcontroller added to talk to the printer. He did a great job of free-forming the circuit alterations and fitting it back into the plastic USB plug housing.The next step was to write some software. Using VB6 he coded an application that loads in an image, scales it to fit, and allows you to adjust the contrast that the thermal printer produces. For testing purposes he’s reusing old receipts. See it in action after the break.

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