Brads Electronic Projects Forum

Hi guys, It's been a long long long time since I have posted here about any of my projects.

So here's my latest project, let's see if anyone can guess what it might actually do.

Here's a clue, top board solders onto the bottom board with headers. And yes, it is a USB stick...

Top Side Under Side

It looks like some sort of USB current sensing device

Are those squares on the top board going to be LEDs? Is it a music visualizer?

Knowing Brad, led's are included somewhere!

Yes you're right bitfogav! it is some sort of current sensing device

Actually it is designed specifically as an inline USB device that goes between your laptop or USB charger and practically any USB device like a portable hard drive, mobile phone, tablet, camera etc...

Saimaster - you are also correct! Those are LED's, in fact they are tiny little 0402 SMD LED's and they form a 5x10 matrix. This matrix acts as the display for the device.

So what can it do?

Well, good question! The ACS712 chip is a current sensing chip that gives you an analog voltage out proportional to the current going through it, it can go up to 5amps. Since the analog output is quite small (around 185mV per amp) this gives a terrible resolution when connected to the ADC input of the microcontroller (which is on the underside of the board). So the output first goes to an op-amp where it amplifies it by a factor of 5 or 6 and then it goes to the ADC input of the microcontroller.

The microcontroller also controls the LED matrix and gives you a scrolling read out of the amount of current flowing, the USB voltage and also power (you cycle between them with the little button that protrudes through the hole in the top led matrix board.

One of the really cool things about this device is that you can switch between standard mode (which just connects the USB D- and D+ straight through) and charge enhance mode (which disconnects the USB D- and D+ lines from the input and instead connects them to the PWM outputs of the microcontroller) this mode will output certain voltages to the USB D- and D+ lines to 'talk' to mobile phones and basically tell them to charge at their full rate.

I have done quite a bit of research into this and found that if you plug an iPhone into a PC or into a samsung charger, it will not charge at the full rate because the USB D- and D+ lines are not talking properly. but if you plug this device in between the iPhone and PC or samsung charger, this will take care of telling the phone to charge at the full rate and therefor it will!

It works for all sorts of phones on any charger, laptop, PC etc...

I'll be sure to keep you updated on its progress!

I have a few of these

brad wrote: Saimaster - you are also correct! Those are LED's, in fact they are tiny little 0402 SMD LED's and they form a 5x10 matrix. This matrix acts as the display for the device.

Brads going small with them 0402 smd's Cool project, where can I buy one? :p

I have a few of these

Yes, very similar to those but better!

I think the thing that makes it really cool is the mobile phone charging capability.

For example, if I plug my iPad into my 1amp samsung charger, it will actually only charge at 400ish mA (because the D- and D+ voltages are not what the iPad is expecting.) but if you put my device in-between the two, it will go all the way up to 900ish mA.

If I used a 2A samsung charger, it would still only charge at around 400ish mA, put with my device it will go all the way up to close to the full 2A (2000mA).

It will also work the other way I.E. using a samsung / android phone with an iPod / iPhone / iPad charger etc...

If that's not enough, i'm even going to put a built in game that you play on the LED matrix

Cool stuff, is this another prototype for kickstarter or something you may look at selling on your site Brad?

Sorry for the late reply Gav,

I was looking to put it up on a crowd funding website, but I'll put the prototype together, print a case for it and see how it comes together

If I can get it all manufactured for a good price then I will look at selling them.

I'll be very interested seeing your case, do you have a 3D printer? and I'm guessing your using a PIC and not an arduino for this project?.

Yes, I bought a 3D printer a few months ago, although I haven't aligned it properly - it takes a long time to set one of these things up!

And yes, I am using a PIC for this project with good 'ol Swordfish Basic! I can't believe that SF has been around for 7 years now! time really does fly...

How's this project going then Brad? have you done anything with your 3D printer yet?

I have to say, life with four kids is BUSY!

I have been working on this project here and there but I just haven't had very much time at all. I have managed to lock in my final design (I am pretty sure) after going through about four different PCB designs - ordered through iteadstudio.

Here is my latest design: I am in discussion with a plastics manufacturer to make a nice housing for this

On another note, someone else has also made basically exactly the same thing and they have it on Kickstarter already. There's is really cool in that it uses a nice OLED display (mine is just a matrix of 5x10 LEDs). There's is more than twice the price of mine though. The Kickstarter special price is $49 and the retail price will be $69. I am planning to sell mine for around $20

Here's their link:
https://www.kickstarter.com/projects/pl ... -92-faster

It's all looking very amazing and professional Brad, damn it about the other Kickstarter though!. I really like the small led's, can't wait to see them in action.. Did you solder them? do you have a reflow oven now?.

I have had a reflow oven for a couple of years now - it is great for projects like this

I originally got someone to make me a mask so I could put it over my PCB, scrape the solder paste over it and then place the components on. However the mask cost me around $30 delivered.

These days I just have a syringe of solder paste with a very fine nozzle. I then just squeeze out a tiny bit of paste onto each of the PCB pads and the place the components on top. It may take a few more minutes but it saves a whole heap of money!

The reflow oven is so easy to use, just put the board in, cook for 7 minutes and out comes a piping hot PCB!