I purchased 2 separate series of 5 MCU’s – the first had weak marking and did not work on a previous breakout board, so I ordered a 2nd batch. The 2nd batch had nice marking, but after trying 3 failing MCU’s I wanted to try the old batch – and voila – it works. The breakout failed because it lacked the VCAP capacitors.
I am also pleased with the new soldering technique that I discovered – I assemble the LQFP’s with close to no error now. Much easier to get right. What I do is to apply paste, but it is always to much paste so I scrape it back of leaving only a thin surface. Once that is heated I use a soldering pen to drag tin over the pins – it is fast, simple and easy to get right.
Regardless, I am very happy to finally see STM32F405RG working! It is to early to conclude that I had a bad batch – I want to try some more before I conclude. Having a working ST32F405 means a lot because it is proof of concept allowing me to plan on using this. With it’s faster processor, 1Mb Flash, 196Kb SRAM it is quite a step up. This reminds me of another silly issue – I have measured the Crystal, but realized that I was not using the MCU’s at full speed due to wrong setting – wow – just felt as if the Turbo hit in.