All MCU vendors will deliver some C code they call “HAL”, while I call that Low Level Drivers (or BSP – Board Support Package) and implement my own HAL (Hardware Abstraction Layer). A proper HAL need to abstract from hardware and secure portability of code. But, most important is that I want to write source code in C++11.

StarUML cost a few bucks, but I like it and it’s the only alternative I have found to do decent UML class diagrams. The class diagrams makes it easier to maintain overview and as such they improve quality of software architecture and documentation + they don’t take much time to draw.

I started learning C back in 1983 and coming from languages like Jovial, Fortran, Basic and Pascal it felt like heaven in comparison. Later in 1994 I learned OMT and C++ that was a good fit and I have been a C++ fan ever since. Yes I use C# and Java as well, but only if I can’t avoid it.

This blog have so far been more about electronics than source code, but I have stated a few times already that this will change. The starting point is 3 libraries that will form the basis of all we do.

The first is HAL – Hardware Abstraction Layer. A library that systematically encapsulate hardware in a functional, abstracted way.

The second library is EFC – Embedded Foundation Classes, a library of tightly written C++ targeting embedded MCU’s. This library was started years ago and have been mentioned before because as soon as I move on functionality I also need building blocks.

I will return to the 3rd library/tool later.

My STM32 Tester finally arrived, and 12 rejected MCU’s which is ca 40% of all STM32F405’s I had is the result. The sent me a different tester than I ordered, but it did the trick. One MCU broke under testing as well.

10 x STM32F405RG cost va 45.- USD from China and ca 90.- USD from Farnell in Norway. With 40% loss and the unknown of factory rejects I can as well just order from Farnell.

To effectively have a small production line you need to have 3 pieces of equipment/processes.

First step is using a stencil to apply solder paste. this can be done with a stencil alone as a mask on top of a PCB, but a better way is to use a 200.- USD stencil printer. This pic show a low cost one for ca 150.- USD.

Second step is to use the pick and place machine to add components.

The last step is to put this into an automated reflow owen. I actually have one of these, but have not used it much because I solder very fast with a heat fan.

I have 2 reasons for wanting to start using the stencil. It is faster and easier to add correct solder paste, and by using the owen I avoid the number of cold soldering problems I have.

I just assembled a wifi board and sat hours fixing 2 cold soldering – soldering that look perfectly ok through a microscope, but actually is not connected. These problems take time and the first step in improving is to actually use stencils and the owen while I ramp up for a full production line.

The drawback is that a PCB that usually cost 5.- USD now will cost 50.- due to the cost and P&P for a stencil with frame.