Weather Station Power

I ran into a little bit of an issue with the old power management system i had installed. The original design was to use a buck converter to drop the battery voltage to 3.3v, this worked fine except the micro controller would not run with 3.3v it needs 5v, so much for reading the manual which said it ran on 3.3v. So then I added a boost converter, except that the BMS would shut down when it was connected.

So onto plan C, i ripped out the BMS, the charge controller and the converter, and am now using an all in 1 unit that is designed to work as shield board for the wemos mini. USB cable will run to the solar panels to charge the lipo’s, the jst connector goes to the batteries and power out is from the 5v pin on the shield. Yeah its ugly, but will work. The 3.3v needed for the sensors will all run off the regulator on the micro. Its a mess, but will work.

Now that crap is sorted, its time to finish off the code and make it work. Thats a job for another night.


Weather Station Update

Ok, so i have been slack for quite sometime and have not really been all that interested in many of the projects that I have sitting on my bench. But its summer, well spring but its 32 Deg C outside so its a matter of staying cool and not be totally bored. So today I am going to do some more work on the weather station and at least have all the modules connected and the code done before i make a house for it to live in and put it out in the garden to do its thing.

So this is where things stand, I have a couple more sensors to wire in and then its off to finish of the code, which after having a quick look at is in pretty good order already and will not be all that much effort to complete.


Arm Programming Cont

I was kind of thinking that the learning curve might be kind of steep. In fact for me its not all that bad, other than working out where everything is in the menu’s the process is rather familiar. I guess all those years programming on MUDS with GCC, GDB, Valgrind and friends using Kdevelop on Linux were not a total waste of time.


Embedded Systems Programming Course

So a week or so ago i was talking with a friend of mine, Simon about how he was wanting to get into embedded programming and what that would entail. He had come across a series of youtube videos that take the unenlightened of us and walk us through many examples of becoming proficient with toolchains that allow for programming ARM micro controllers.

Now, I can do quite a bit of superficial programming in C using the arduino, but it does hold your hand quite a lot and its great for simple things, but if you want to do anything serious you really have to man up and learn how to use IAR Workbench or some GNU C toolchain along with all the associated hassles that come with that.

For sometime I have been using STM32 and ESP8266 micros but wimping out and using arduino for programming those chips, but after seeing this course on how to do ARM programming using the right tools, I have decided that its time to give it a go and see if I can get my head around the whole idea. So i ordered the TI development board from Element 14 and it arrived today so now there are no excuses. Time to start learning ARM programming and perhaps soon i might be able to turn those new found skills into a DSP IF board for homebrewers. No promises, failure is always an option 🙂

And here is the link to the course ware for those who might be interested in all this as well and want to give it a crack.


TDA2822 Audio Amp

So I have had this pile of Ebay sitting on my desk for sometime and today I have gotten excited enough to actually start taking a look at it all and seeing how it works. I got these frequency generator chips for like a buck and after setting them up with the test circuit, i could not get them to work, it happens, now and again you get Ebay’d in the butt.

So I figured next i should test out the TDA2822 audio amps. I for 50 for 2 bucks which is a lifetimes supply. Do they work, well, yes they do and here are the results.

Here is the test circuit straight out of the PDF. As you can see parts count is low. So I put the IC on the breadboard and used just 1 1/2 for a mono amp. I also used just 2 caps, pin8 to ground, 470uf as it was already on the breadboard and the input cap on pin 1. Powered with 8v as its a handy voltage i have on my breadboard. 12v would probably be a better option to allow for a larger voltage swing.

As you can see, nothing fancy here, just the IC and 2 caps and my signal gen and oscilloscope probes doing there thing allowing the pixies to in and out and display them in the screen.

So we stick in 0.1v 600hz sinewave and see what happens.

Well, we actually hit the voltage rails and clip somewhat. 0.1v in almost 8v out, that is the voltage gain there. And when i do some da finger poken, the IC itself is cool to the touch, not warm, not hot, but about the same as ambient temperature of the room. So i am thinking Bye Bye LM386, and hello life time supply of TDA2822. And being a stereo IC, I can also bridge the left and right for even greater output. Not that I think i would need it.