nuxx.net blog

I’ve been working on a video camera system for my bike. The project is just getting started, but today I made the PCB for the power supply. You can see it above fit inside of its project box (a RadioShack 3×2x1″), or you can see the bottom side with solder and traces here.

It’s been a few years since I last etched a PCB, and as I’d run out of photoresist developer (a lye solution) I decided to make due with what I had readily available and laid out the board by hand, drawing it in pencil and marker and using nail polish as resist. I’m quite happy with how it came out. The many-year-expired tin plating chemicals that I had sitting around the basement even worked, giving it a nice tarnish-resistant silver finish.

This PCB and housing is designed to hold two eBay special step-down DC to DC switching regulators (buck converters) to get 5 VDC and 12 VDC from a 14.8 V 3000mAh LiPo battery pack. The 5V will power a SanDisk V-Mate solid state video recorder and the 12V a VioSport Action Cam 3. All of this together with an 8GB microSD card should allow for the continuous filming of eight to nine hours of mobile video while fitting in a small bento-style bicycle bag.

Now to wait for the rest of the parts to arrive so I can put it all together. The camera and recorder are here, I’m just waiting on the hand grenade battery and charger, bento bag, regulators, and powerpole connectors. Hopefully this won’t be too bad for a ~$200 project. The video quality should be decent as shown by this intentionally shaky test which features Danielle and Roxie (warning: contains dog nose) and single-charge recording length should be long enough to capture any bike ride that I might choose to record. More photos are available here, if you’re interested.

With this shipment the very last SDrive NUXX is sold, and the project is complete. The bare PCB on top is the first / prototype device with retrofitted ZIF socket. I may use it for future development work, or I might just keep it around as a memento.

Now, time to find another project.

In other cheap Chinese device news here’s DealExtreme p/n 8422 with the case removed, powered by a benchtop supply, peered to my Nexus One, and playing audio. I’m hoping to redo the output circuitry on this and put it in another case to make a decent Bluetooth audio device for connecting to either a home or car stereo. It runs off of 3.7 VDC and has an on-PCB antenna, so it should be pretty easy to work with.

The PCB contains an I.S.S.C. IS1621N and FM24C08B EEPROM, which likely contains the IS1621N’s config. I’ve requested the data sheet for the chip from I.S.S.C., so hopefully I’ll have that soon and can work on it. I’d also like to change the identifier string in the EEPROM, but I probably won’t touch that until I know what the IS1621N expects to find in other parts of it. I also hope to find an example implementation, as it should be easy to build off of that to get line level output.

Here’s a few more pictures of the board:

· Detail of the FM24C08B EEPROM which likely houses the config for the IS1621N on the BCK-08.
· Top / button side of the BCK-08 PCB.
· Bottom / component side of the BCK-08 PCB showing the I.S.S.C. IS1621N Bluetooth IC and FM24C08B EEPROM.

I guess this is what I get for buying discount ZIF sockets on eBay: one “genuine” TFXTDOL-brand DIP28 ZIF socket. It’ll probably be fine, even though I had to fight with pins which are too wide for sockets and almost too wide for the drill holes in one of the SDrive NUXX prototype boards.

Having some time this evening I opened up the ultra-bright LED-bearing faceplate from Danielle’s new car stereo. I was originally hoping to replace the LEDs with red or green ones, but after seeing that some are part of the tactile switches I decided against that. Looking into things by plugging the bare PCB into the head unit (photo) I found that the most offensive LEDs were those under the horizontal translucent buttons, with two of them lighting each button, and the ring around the chromed selector dial.

The decision was made to remove one LED from under each of the translucent buttons and one from around the ring. The LED removal went well, save for discovering that the ring LEDs are wired in series, so removing one turned off the entire ring. Still, the final result is much nicer. The stereo now lights up blue, but it’s no longer a glaring blue which makes seeing the road at night difficult. If you compare this photo from last night to this one from tonight you can see how much more reserved (and appropriate) the illumination now is. The loss of the knob ring illumination isn’t really a concern, as it’s the only knob on the device so it’s easy to find and other light glinting off the chrome finish makes it easy to see anyway. The tradeoff for less irritating light is worth it.

Interestingly there were two discreet sets of solder pads for each LED, and some silkscreen on the back that indicated selections for amber and green LEDs. I suspect that other similar models of this stereo offered the other illumination colors and this particular model was just for Target, or perhaps low end markets, or something like that. Or maybe this board is just fitted differently when used in other higher-end models…

Ever since getting an iPod Danielle’s been wanting a way to connect it to her car. While at Target today I happened across a Sony CDX-GT43IPW on clearance for $69.98, and a few hours later it was installed in her car. Installing an aftermarket stereo in a 2000-ish GM J Platform normally requires some wiring trickery so that the factory chime sounds aren’t lost, but thanks to Danielle’s car already having an aftermarket stereo I was able to simply adapt the old wiring harness to this stereo’s needs, resulting in the harness seen here.

Disassembling the dash to access the stereo was also a bit of a hassle, but easier than expected. The stereo worked on first go, and the iPod interface is surprisingly decent. The built-in menu system which manages the iPod is about as good as one can get from a one line display, and there’s another mode which simply allows the iPod to controlled directly. There’s also a standard 3.5mm Aux In on the faceplate, should she wish to hook up another device that way.

The biggest down side is the ultrabright blue LEDs which illuminate the controls on the front panel. For now Danielle just ignores them while driving, but I imagine they will get pretty irritating soon. Sometime tomorrow I’ll probably open up the face plate and check out the LEDs. Hopefully it’s easy enough to open and they are pretty easy to replace. Green or red, and much less bright, should work out well.

With Google’s release of the Nexus One it worked out very well for me to give my G1 to Danielle and pick up a Nexus One for myself. Thus far I’m quite happy with this phone. The AMOLED is absolutely outstanding and the phone is simply faster overall; the occasional quirky slowdowns when using many apps at once are gone.

It even comes with a cute logo’d neoprene case, as seen here!

I still have some service plan shuffling to do, including moving myself to an employee discount plan (via my workplace) and possibly another service plan. While I am out of contract and should be able to move plans at will, it appears that T-Mobile has a $35 fee to change plans via their website and I don’t want to pay that. We’ll see how that goes… Until then, the phone still works great, just like my old G1 but even better.

(Photographing a phone with active screen and having both parts look nice together is a very difficult task. More photos of the phone unboxing can be found here. I’m not bothering with measurement / thickness / whatever shots, as those are thoroughly addressed elsewhere.)

Today my NiteRider TriNewt headlight was returned after being sent out for repair. NiteRider actually replaced the cable which had a short, replaced the switch, and sent a new helmet mount; all under warranty and free of charge. I was a bit surprised at the switch replacement, although in retrospect I had noticed that it felt a bit odd. I’d previously thought that I simply wasn’t familiar with its operation, but it turned out to be faulty as well.

As can be seen above it was also tested, with the battery illuminating the light for 3:16:00. I presume this to be on high, and this is plenty of time for my uses. Now I can get back to riding more at night. I’ve was loaned an HID which I’ve used from time to time, but being prone to fall damage and not being my light, I was hesitant to take it out very many places. Hopefully tomorrow evening when the weather is a bit nicer I’ll be able to head out for another ride.

As part of rewiring my office I purchased this seven-port USB hub from Firefold for $22.99, part number USB-7P-HUBSP. It turns out that this hub is actually two Genesys Logic GL852G hub chips, with one cascaded off of the other. The three ports shown above on the left are connected to the first hub, then the other four are connected to the second hub chip. Thus when the case is closed up (as seen here) ports 1-4 are on one hub which is connected to the hub that ports 5-7 are on. This shouldn’t cause a problem, but it’s a much cheaper design than using a seven port hub chip and having everything at the same level.

The hub also ships with a 5V 2.5A switching power supply. Having seven ports which can supply a maximum of 500mA each, this power supply cannot fully power the hub. That said, most devices never pull anywhere near 500mA, so this shouldn’t be a problem either.

Tonight was a perfect night for a ride. Beautiful clear skies, upper 50s, and a light breeze greeted us as we rode from my house to River Bends Park to poke around the new limestone path and some unofficial single track. Not long after entering the park we even ran into some other people we knew who were out enjoying the same trails.

Heading back into the woods things were going well, until I ducked some overgrown brush and caught my head light. While I stayed on the bike, my NiteRider TriNewt stayed with the brush for a bit, breaking off the mount and apparently stretching the cable to uselessness. I was then left holding a non-working head light, roughly two miles into overgrown single track trails which were frequently bench cut along ponds. Thankfully the two people I was with rode behind me, so I was able to see well enough to make it out, even if some of those points involved ensuring that the front wheel was pointed at the narrow, dark shadow in front of me.

Once we made it back to the wider limestone / paved paths in River Bends things were much easier, and I was generally able to ride along next to people, using overflow light to see by. We were then able to finish up a nice loop, totaling ~17 miles. I’m quite lucky that I wasn’t out alone tonight, as a broken light six miles from home on trails would have meant lots of walking and not-safe riding.

Tomorrow I’ll try contacting NiteRider about getting the light fixed. Per their warranty website this should cost $30 in bench time, plus a new cable and light mount. I opened up the light briefly to check for broken solder points, but everything looked fine, so I suspect the cable. Since the cable and its strain relief is not something I can easily remold myself, I think I’ll just pay them to do it. Hopefully I can have it back quickly. Until then I will probably be using a borrowed HID, which should be interesting. There’s a reason why people are moving in droves to LEDs for bike headlights.