Tuesday 24 February 2009

Board in from manufacturing

So we received our big beautiful board back from manufacturing and it's cool. This is the first project I've worked heavily on, with regards to design, researching components, sourcing components and verifying correct connections. It's a very dense board, there's barely any room for any other additions and everything is packed tight.

Anyways, when a new board like this comes in, the last thing we do, is power it up. There's a whole load of tests that need to be done first. First test is to check what parts are missing throughout the board. Then we must check to make sure that the components that should not be populated on the board are not there. At the same time, where these devices shouldn't be, there should still be a pad if we need to add a component at a later stage of testing.

Next step is to check the orientation of all the tantalum capacitors, ensuring that the positive is connected to the correct power line. Orientation checks must also be done for all integrated circuits, diodes, LED's, inductors, crystals and any transistors or 3 legged circuits by carefully observing pin 1 against the board file (created before manufacturing by our SI team).

Next we need to ensure that there are no shorts between the power lines ranging from 0.9, 1.2, 1.5, 1.8, 2.5, 3.3, 5 and 12 volt lines. Ideal resistance should be greater than 400ohms, unless there is a sense resistor involved (these need to be worked out exactly), but there should never be a complete 0ohm resistance between any two planes.

Checking these same planes, we verify them against each other to make sure there is no shorts between each voltage plane. Rules go the same as I mentioned above for checking ground shorts.

After all these checks have been and the necessary components have been fixed, it is now possible to power on the board and perform voltage checks throughout the board to verify correct function of all the DC-DC converters.

The rest of the tests after this become much more complicated and specific to each project depending on what IC's there are on the board and the device's functionality and specifications.

All in all, this board is going to be very interesting for me, I know most of the parts already and what they should be doing, so I'm not completely in the dark this time.

3 USB modem (E169g)

Since moving into my new apartment, I've been mad to get broadband in the house. None of the others were interested so I figured now I could get a line all to myself. However, there's no phone connection in my room and setting up a land line broadband connection would cause more hassle and annoyance that I don't want to create.

So I searched around for wireless broadband. I've heard of a few Clearwire, Irish Broadband, Digiweb and a few others. They all seemed pretty expensive to me and I know all about the problems with Irish Broadband (I used to work for them and I will never use them as an ISP, enough said). I didn't really like the sound of any of these. Too pricey, fixed contracts and a service history to cringe at.

Then I found mobile broadband. I'm not saying it's the light at the end of the tunnel, but its a nice little package. The Huawei modems from O2, Vodafone and 3 seem to be the more popular modems out there. Having done a little research, 3 seemed to offer the best pricing and service out there. 20euro a month, E169G modem is free upfront and the day I joined, they had just upped their cap limit to 15GB so I was very happy that day. It boasts download speeds of up to 3.6Mbps (apparently possible to achieve up to 7.2Mbps on online forums). I was told that 3 have a deal with Vodafone and they share their mobile infrastructure. My only worry was how decent a signal will I receive from my house? They were only able to tell me that they cover all of Dublin. I figured that'd be good enough, with a 14 day option to cancel the contract, I went for it.

All went well for the first few days. I was able to download anything I want, no limits on various programs using the net, no blocking of ports. I was very happy until AVG asked me to download the latest virus definitions. Then for 2-3 days I was without internet, trying desperately to unplug, replug it back in, restarting the computer, uninstalling programs that I thought would affect it. I finally gave in and phoned tech support. The tech support guy was very helpful and stayed for full resolution. He informed me that some Anti-virus software programs conflict with the device. I was annoyed to hear this, but figured I don't get much trouble with viruses anyway and proceded to uninstall it. Finished the call and thought all was fine until the next day, it wouldn't work again. I eventually went into msconfig and selected Selective startup (unticked the box where it says Load Startup items) and I've left my PC like that ever since. It works, I'm able to run everything I want and I'm happy for the moment.

Except now I want to be able to use it in my installation of Ubuntu. I've searched the web for some explanations and tutorials (Ubuntu Forums)and I'm going to have a go at it later. I've heard rumours it works faster too. I can but hope. More on this when I get it working :D