Recent content on Alvaro's Blog
Do you have a J-Link Compact and have noticed it doesn’t work with some USB C to C cables? I do, and I did, so I decided to investigate… Background The J-Link Compact is a really nice debugger for various microcontrollers. The non compact version is rather large and uses USB-B(or Ethernet). It comes with a branded ~1m C to C USB cable, which works great. I plug it into my laptop, the…
Have you ever wanted to debug your microcontroller over USB-C? (I’m talking JTAG/SWD, not just USB!) If you already have a USB-C connector, there’s no need to have an additional connector to program! (or Tag-Connect pads, which are super nice, but take up additional space) I’ll explain how I did it below. NOTE: Much of this was originally a few Twitter threads back in 2022.…
Quick Note This was originally a Twitter thread back in March, 2020. After reading Molly White’s post about POSSE ( P ost (on) O wn S ite S yndicate E lsewhere), I’ve decided to start posting everything here and just linking from other sites. I changed a few things so it makes sense as a blog post, but the content is practically the same. Background A few years ago, I found my dad’s…
Ever wonder if your USB C cable is USB2 or USB3? Do you have some charge-only cables hiding in a box just waiting for the right moment to spoil your project plans?! Fear no more! I’ve made a simple board to test most of the things! (This post is derived from my original twitter thread about it.)
It’s been over a year since I wrote about my weather station project. A lot of things have happened since, so I figured I would post an update. Soon after returning from Mexico, I started thinking of the next version of the board. I didn’t want to continue using the XBee radios, so I decided to try out bluetooth again… In order to continue having a working weather station I kept the…
I’m not sure exactly when I became interested in building a weather station. It was at least year or two ago… I remember seeing the Project Curacao 2 post on the SwitchDoc Labs page and thinking it would be fun to build something like it, but much more integrated. I’ve also never worked on “outdoor” projects and want to learn more about weatherproofing, solar…
Nui is an IR controlled volume controller for analog audio. It sits between your audio source and speakers and can amplify or reduce the volume using IR commands (and eventually BLE). Why do I need this? It all started because I have my trusty Logitech Z-2300 speakers and subwoofer I purchased back around 2004/5. They still work great, but instead of being on my computer, they are used for my TV.…
As you might, or might not have, heard, I left my last job in May. It wasn’t an easy choice., but after thinking about it for a very long time, I realized I wasn’t happy where I was and needed a break. When I had to explain my “employment status” to people, I decided that the term self-funded sabbatical was the most appropriate. Looking back almost 5 months later, It’s one of the best decisions…
A few years ago, I bought a couple of these analog gauges(galvanometers) at the electronics flea market . Like many other things I buy, they ended up in a box stored away in the closet… Not too long ago, stumbled onto Alan Wolke’s ( @AlanAtTek ) video about panel meters After watching Alan’s video, I decided to pull the gauges out and see if I could make them do something useful. The…
What is this? These are instructions for getting the Xilinx tools up and running on OSX to work with the Embedded Micro Mojo v3 FPGA development board. Why am I doing this? I bought the Mojo v3 development board last year to start playing with FPGA’s but haven’t gotten around to using it. I figured now is as good a time as any to start… Why not just dual boot into Windows or…
This year’s work holiday party was Back to the Future themed. I didn’t have any good costume ideas, so with a week to go, I decided to build a portable flux capacitor to bring instead. The first thing I did was to order some addressable RGB LED strips online. I bought some clear tubing at the hardware store and cut the LED strips to size. I then used a Teensy LC that I got at the…
After last years DEFCONBOTS competition, I decided to try something completely different. (Check out last year’s robot .) Having to move the entire turret/camera/laser around is incredibly inefficient. If the goal is to shoot things with lasers, the only thing moving should be the laser beam. While doing some research, I found various projects with home-made galvanometers . I did not trust myself…
The last turret update (with actual content) happened back in February. I continued working on it through August, taking it both to Maker Faire and DEFCON. I had planned on writing about it back then, but never really got around to it… This post covers the mechanical aspects of the project. I’ll write about the electrical/firmware/software some other time. The last post covered some initial…
I just switched to using Jekyll instead of Wordpress for this site. I started hosting it on a VPS and don’t want to have to deal with all the apache/php/mysql security issues. Now I just use Jekyll to make a static site and run it on nginx (the nginx part was just for fun). There might be some bugs due to the importing of old posts from wordpress/blogger. Let me know if you find one so I can…
I’m still recovering from Maker Faire last weekend. Here’s a quick video about the laser shooting gallery we set up. The laser turret was there as well, but playing against other people was much more entertaining. Time permitting, I’ll post details about the exhibit and how it works.
Over the past month, I’ve been working on a laser turret for the DefconBots autonomous robot competition this Summer. I entered the same competition back in 2006 and enjoyed the experience, so I figured I’d give it another try. Since I am fairly comfortable wiring firmware, I plan on focusing on the mechanical aspects of this project, as well as the image processing (both of which I know little…
I’ve been using the Dangerous Prototypes Bus Blaster along with openOCD to program/debug my LPC1769 microcontroller. It’s been a while since I did anything, so when I tried again last week and couldn’t get it to work, I was slightly confused. The only change (that I was aware of) was an OSX upgrade from Mountain Lion to Mavericks. Whenever I tried to run openOCD, I would get the following error:…
A few days ago, I found out that you can send video messages to people via Skype. Someone asked me if I knew of a way to export them from Skype. (That way you can watch them while offline, back them up for later, or whatever else you might want to do.) After searching around the web for a while, I realized that there is no such feature at the moment. I also saw many people suggesting an SQLite…
Soon after I bought my Kinesis Freestyle 2 Keyboard , I noticed that the media keys (next/previous song) did not work with Spotify on OSX. The strange part is that they work just fine on iTunes. I decided to email the Kinesis tech support to see if they had a solution. Kinesis support was extremely quick to respond and informed me that this was a known problem and was fixed in the latest batch of…
After getting the gcc-arm compiler working with the mbed , I decided to take a look at my LPCXpresso LPC1769 development board. The mbed is really easy to program. It mounts as a flash drive and you just drag and drop the binary file onto it. Unfortunately, that’s it. There is no way to get any debug information out of it. The LPCXpresso, on the other hand, comes with a nice LPC-link board…
Don’t want to read though this post? Just want the code, go get it from my github repo ! I’ve been meaning to start working with Cortex-M3 processors for a few of my projects. Sometimes the MSP430’s I usually use just aren’t fast enough. :-) Previously, I’ve used the mbed (discontinued in 2026), which is a nice Cortex-M3(LPC1768) development board. The best part about…
If you haven’t heard about my ‘home automation’ project, you should probably read this first . This weekend was rather productive. I managed to get my light alarm working! I wrote escheduler , which is something like crond , but calls functions, instead of running programs. It’s also more limited, since it only schedules events on a weekly basis. Escheduler runs on the…
I’ve been neglecting my projects for a while, but I finally decided to stop being lazy and started working on them again. Several of my old posts deal with msp430’s and cc2500’s , but they’re mostly hardware updates and examples of changing lights to music. Now that I have a semi-stable platform and decent libraries, I figured I might as well do something useful with them.…
I recently found out that the San Francisco International Airport (SFO) offers bike parking for up to 14 days. I decided to try it out during the thanksgiving break just for fun (with the added bonus of saving on driving/parking or taxi costs). The San Jose airport is much closer to where I live (San Jose/Cupertino area), but SFO has more direct flights to where I need to go. SFO is over 40 miles…
I recently started working on a project that might require some Passive Infra-red (PIR) sensors. Sparkfun had two different ones, so I figured I’d try them both. The comparison is between a Zilog ePIR and an SE-10 . One very important thing to note is that I did not use the ePIR ’s serial interface. I only used the hardware interface, set to the highest sensitivity, and shortest delay.…
The Wireless Friend Finder was my project for the Bring-a-Hack dinner after the 2012 Bay Area Maker Faire . I made it in a hurry, so it’s not terribly well documented. The wireless friend finder is a device that will start buzzing when another device gets near. This can be used to find a friend in a crowd(or to stay away from someone you don’t like)! Here’s a quick video I did…
I finally decided to get a dedicated electronics workbench. I had been working on my computer desk until now, but it wasn’t quite working out. The first problem was having to clean up my electronics gear all the time, so I could have space to work comfortably and have other stuff out. The second was that it’s a glass desk, so I had to be really careful not to break it (No hammers!).
I finally managed to make a quick video of the build process for my wireless RGB LED controller. I used two cameras to do a time-lapse of the build. Unfortunately, they were using different frame-rates, so it took me a bit to get both of them synchronized. If you’re curious how the setup looked, here’s a (bad) picture of it: I uploaded the EagleCAD files for the board(schematic and…
I just spent several hours debugging my cc2500 radio libraries . What changed you might ask? Two lines of code… My Wireless RGB LED driver had been using the msp430g2452 microcontroller. So far it has been working great! Someone emailed me asking about the msp430g2533, and how it wasn’t quite working. I currently use the msp430g2203 (which is a cheaper variant of the 2533) as my…
I’ve been working on my wireless RGB LED boards for a while now. I finally made an all-in-one PCB that includes an msp430, a cc2500 radio module, 3 MOSFETs for driving the LED strips and a 3.3v linear regulator. I know it’s not the most efficient setup, but right now I want to focus on software and need hardware that just works. The design is really simple. 12V in are passed through…
I recently migrated my blog from blogger to WordPress. The migration was extremely easy with the automatic importer in WordPress. The only problem is that every single link on the web is pointing to the blogger generated permalinks, which do not match the new WordPress ones. Since I still get some traffic from other sources, I decided to come up with a method to have the old links redirected to…
I received my PCB’s yesterday (From Laen at dorkbotpdx.org , of course!). I spent last night attempting to solder all the surface mount components (and for the most part, failing miserably). I need to get some solder paste and a small oven for the next batch… After soldering all of the passive components and msp430’s, I began the first set of tests. First I checked to see if all…
Here’s another quick update (with lots of pictures and a video!) I ordered another RGB LED strip from adafruit in order to test how my system works with multiple devices. I don’t have my PCB’s yet (I shipped them to NY by mistake…), so I had to build everything on breadboards. The main problem with my previous design is that it required two separate power supplies. The LED…
My current apartment has one of those ‘smart’ electric meters that can communicate with the power company directly over the power lines. A few months ago, I found out about a smartmetertexas.com , which lets you register and get logs of your power usage in 15 minute increments. I thought that was really awesome and signed up. The concept is really cool, but unfortunately, their user…
I managed to go flying last Friday after work. Since no one else was able to come along, I decided to do some experiments with the camera. Last time I mounted the camera on the rear window pointing out. This time I pointed it toward me, instead of out the window. I did a time-lapse of the first half and later on an actual video of the landing. Not too interesting, but I figured I would share them…
So I wrote last week about getting UART working on the MSP430G2533 but having major problems with the SPI interface… I was so frustrated that I caved in and purchased a Salae Logic analyzer. It finally arrived today, and I had a chance to test it. As soon as I opened the box, I connected it to sniff the SPI lines between my msp430 and cc2500 radio. It took me maybe 10-15 minutes to set up…
This post is mostly about software, so I’ll keep it short. I re-arranged most of the code so it hopefully makes more sense. My goal is to make the main code hardware agnostic. That way if you want to use a different device, you just change which drivers you’re using, but your main code stays the same. Eventually I’d like to be able to support multiple devices from multiple…
I haven’t been working on this project lately, but I finally got back to programming yesterday. I got the MSP430G2533 which has both hardware UART and SPI. This one will act as a bridge between the PC and the CC2500 radio. It could also be used to drive a serial LCD. I managed to get the UART working, but for some reason I’m having trouble with the SPI communication with the radio.…
Here’s an even smaller update! Since the MSP430G245 2 doesn’t have a hardware UART, it’s not very useful in communicating with the computer. I could use the bit-banging method to get 2400baud, but I didn’t feel like figuring it out. For my thesis, I implemented a serial-to-radio repeater using the EZ430-RF2500 and a USB-to-serial converter. I was able to modify the code to…
Here is a quick update on the project’s progress. Today I was able to get the radio libraries working better and actually set up constant radio communications across a room. I also wrote an RGB led controller using PWM and combined them together. Here’s a brief video of the result: So far it’s just one microcontroller generating RGB values and sending them to another one. Now I…
So I’ve started working on another project… This one includes microcontrollers and radios. The “goal” of the project is to have a very cheap 2.4GHz radio module and libraries to use it. I used the CC2500 radio module for my thesis project, but it was part of the EZ430-RF2500 development kit. The kit itself is nice, but at $20/device, it’s not the cheapest. My first…
So I had a few days off work for thanksgiving… Most people usually visit their family during that time, but due to a late change of plans, I ended up doing something else. I found out that about 600 miles west of Houston is a town called Fort Davis, Texas. Near this town is the Davis Mountains State Park and the McDonald Observatory . Since I hadn’t seen a clear night sky since I was…
I recently started experimenting some more with time-lapse videos while moving. I bought a suction cup mount for my DSLR and tested it out in my car. Here’s a very rough test of the car setup. I just wanted to see if the mount stuck to the window and didn’t fall with the rough Houston roads. I also tested it on a quick flight around the area. Since it was a bit gusty, the video shakes…
I have been working on a few projects recently. Two of them involve having custom PCBs made. I’m currently waiting for them to arrive. In order to prototype and test the circuits, I had to order a bunch of parts, so I took advantage of the buying spree to get myself some better tools. My favourite so far is my new Agilent U1251A Multimeter. After seeing the great review of the U1253A (which…
A few months ago, I found out that my school offers a diving class. I enrolled and was having fun for a few weeks until I messed up an entry off the 3m board and hurt myself. I didn’t notice initially, but the next day my hip was hurting a lot. I went to the doctor, got some x-rays, and began physical therapy. There was no bone damage, so they figured it would sort itself out with the…
I recently purchased a Casio EX-FH100 digital camera. Unlike most other point-and-shoots, this one can do high-speed video. It ranges from regular 720p HD video at 30fps to high-speed 120 fps(640 x 480), 240fps (448 x 336), 420fps (224 x 168), 1000fps (224 x 64). The resolution on the fastest two is pretty bad, but it’s still fun to mess around with. After testing the camera on myself…
I’ve decided to actually write about what I’ve been up to in the past few years. Today, I’m going to start with a project from the summer of 2006. I decided to go to DEFCON and take part in the defconbots competition. The main goal of the competition was to build a device that shot targets using autonomous control only. You can see the competition page here and the results . Unfortunately, I…
I still haven’t written about my Svalbard trip. Thankfully, I took some notes while I was there, so I will not forget the important details by the time I do write it. Stockholm My last week in Finland was great. I worked more than usual in order to have my final presentation on Wednesday August 25th. The next day I left Tampere and went to Turku to catch an overnight cruise to Stockholm with…
I am writing this in an internet cafe in Oslo… Svalbard was amazing! I will probably write quite a bit about it when I return and have some time. I also have hundreds of photos to upload, which will also take some time. Some quick things: I did not see any polar bears :-/ Two kayakers did in June, when one was dragged out of their tent by the bear! I did see lots of other animals though. I…
Saturday August 7th My day started at 3:50am when I woke up. I had set my alarm to 4:00am, but I woke up before it anyway. The reason I woke up so early is that I live in Tampere, but had to catch a ferry in Turku at 10:00am. The only train from Tampere to Turku that was available left Tampere around 5:55am. In order to take that train, I had to take a bus to get to the train station. As you might…