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Showing posts from November, 2005

Microscope for SMT

Here are a few pictures of an early Birthday present from my wife:

The 10x magnification makes it perfect for soldering and inspecting smt. I was able to hand solder the 208 pin 0.5mm pitch Xilinx Spartan 3 FPGA used on my HPSDR board in under 5 minutes which included inspecting each pin. If you do any serious smt work at all, you may want to consider purchasing a similar microscope. I was amazed at the difference it made in speed and comfort while working with fine pitch parts. (Price is about $214 + shipping).

Some notes on soft real-time under Linux 2,6...

Linux 2.6 Kernel:

With the 2.6 kernel, a large step was taken to improve Linux's real-time capabilities. The improvements are a result of two major changes in the kernel (as well as many minor changes):

1. Kernel preemption. Before 2.6 the scheduler was able to preempt threads running in user mode, but when the thread made a system call that caused a context switch to kernel mode there was no way for the thread to be preempted. This situation could cause a high-priority thread that was ready to run to be blocked by a lower priority thread inside a system call. With 2.6, the kernel can now be preempted.

2. Constant time scheduler. Prior to version 2.6, the time that it took for the scheduler to decide which thread to run depended on how many threads that were currently running on the system. The more threads on the system, the more time it took the scheduler to make a decision. In version 2.6, the scheduler makes the decision in the same amount of time whether there are 1 thre…

Schematic and PCB software update

Recently I came across the open source Kicad project. I had evaluated DipTrace which is inexpensive but it is not open source. I then worked with the open source gEDA tools which were ok.

Kicad looks very promising:

It is cross platform and uses wxWindows. It is much more polished than the gEDA tools. The file formats are all well documented which make adding symbols very easy using a python script. Kicad's source code build process stinks but fortunately there are binaries available. When I get a chance I will look into creating a Visual Studio project for Kicad so it can be built more easily on Windows.