I love MCUs. I mean that I really LOVE them. Working with micro-controllers combines a hobby (electronics) and my day job (developer) in a way that nothing else really can. The MCU market today is really crowded – which is great if you want to narrow down the perfect chip for your project, but it also means that getting dev kits to see which options are best for your projects can be really expensive.
A new project came up for me, so I decide to build my own dev kit. It is not as hard as you think and gives a lot of bang for your buck!
The ESP-12 series chip (based on the ESP8266) is NOT breadboard ready so you need to either piggy back it onto a home made adapter using headers and stripboard/protoboard or else order an adapter. I ordered a set of adapters and it worked well for my purpose. I also used a YuRobot power supply with the breadboards to provide power. I use them because they’re cheap, not because they’re great – they tend to die out over time and the initial failure rate for me is usually 40% – meaning I get 3 for the price of 5. But they’re cheap and they get the job done!
I used my USB microscope, displayed on my 4k monitor, to give fine detail for the project. I’m soldering using my Weller TC202 and a roll of my Dad’s Kester .025 resin core solder. I’m using a breadboard to hold everything in place while I do the soldering.
As always, click the image to view full size in a new window/tab.
The first picture shows the adapters, headers, and MCUs on my soldering pad (anti-static, heat resistant silicone). The second pic shows headers on the breadboard, with one adapter in place before soldering. I put a probe on top of the PCB to hold it down while I quickly soldered a pin on each side to anchor it.
Here are a couple of shots from the microscope. My screen caps didn’t work well for some reason, so I took a couple of pics with my phone. It loses a little in the translation. But you get the idea. Here’s the finished adapter.
I plugged the adapter back into the breadboard to keep everything stable. Then, I put a couple of small blobs of solder – one in each corner – so that I can tack down two corners of the MCU module in the second picture. Remember – you only need a tiny drop of solder, the idea is to stay inside the dimensions of the pad on the PCB. The other two pics show the image from the microscope.
These pics show the MCU soldered onto the adapter. I used a small drop for each “pin” and gently slid the soldering iron from the module to the adapter. I repeated this 2 to 4 times for each pin to make sure that I end up with a good connection.
Next, I add the breadboard power adapter module – I will need to supply 3.3 volts to the dev board.
So the first part of the project is all done. The next task will consist of powering up the dev kit to make sure it is assembled correctly, connecting it to a PC for test firmware, and setting up a basic circuit or two on the breadboard to validate!
Why do you want a dev kit? Good question. You use a dev kit to test out your concept. This is also called prototyping. There are multiple stages of prototyping, but it is smart to start off with a dev kit when working with an MCU. You test the electronics and write sample firmware and see if your idea is viable. If this stage is all you need to reach your goal, great! But, if you need to set up protoboards/stripboards or even design PCBs, it is a good idea to have the circuits set up and tested with a dev kit in order to simplify tasks later on in the process.
In the past, I used Texas Instruments chips for my projects. The Launchpad ecosystem is very rich – lots of code examples, two full featured IDEs, one of which is based on the Arduino framework, and active communities full of engineers, noobs, and everyone in between. However, TI isn’t the best choice for projects where you want to keep cost minimized.
In the last couple of years, the ESP8266 from Espressif Systems has blown the doors off the MCU world. It is now the go to choice for most Wi-Fi IoT projects and products, for very good reason. It is produced in staggering volumes, so the unit cost for some variations is tiny. It has an ADC pin, plenty of GPIO pins, TCP/IP stack, and comes in several module formats – some already with FCC and CE certification and extended range PCB antennas.
The chip I’m working with is the ESP-12f. While there are great uses for the different variations, and there are differences in the specs for each version of the chip, the software side is virtually the same. I haven’t gotten my hands on an F chip yet, but have the E and the N, so I’m going to use those two to build dev kits until I get my hands on the F variant.Parts List:
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