How to make prototype circuits that include microcontrollers, and avoid breadboard annoyances at high frequencies

breadboardhigh frequencymicrocontrollerparasitic-capacitanceprototyping

From my searches of the web ( as well as this question ), I have found that breadboards – like the one on picture – aren't a good idea when your application involves high frequencies.

Breadboard

I am going to start making simple projects using STM32F407VG microcontroller, that can operate at frequency of 168 MHz. Although pin switching won't take place at this maximum frequency, it will still be very high, in orders of tens of MHz I assume. I have STM32F4 Discovery evaluation board, but will connect external circuitry to it as well.

My questions is : how should I build prototype circuits to avoid problems with parasite capacitance / inductance, if using breadboard is a bad idea ? Thank you.

Best Answer

Fortunately, if you're using the internal clock, that 168MHz doesn't ever get to the breadboard. Think of your max frequency as what's going on at the pins.

For that processor, though, the simplest way to go is to pick up the stm32f4 discovery board for about $15, and do your prototyping with that. The useful pins are all broken out for you.

To get the signals you need from the Discovery board to something you can get at more is easy. I like using 50-pin ribbon cable breakouts. I use them to bring signals to breadboards, but they'll also bring them to solderable things like vectorboards. The ribbon cable, of course, attaches directly to the Discovery board headers.

This is all intermediate steps, of course. Eventually, when the bits and pieces of the design are all finished, you can print up a PCB with confidence, and move everything there. If I may offer advice, though, a 100 pin package with 0.5mm pitch isn't necessarily the friendliest way to break into surface mounted devices.

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