Long story short, if you don’t have the software uploaded into the microcontroller, there’s no way to turn the device on. To do this I have designed a power switch that doesn’t need the microcontroller to be powered, but uses the microcontroller to keep the system powered once started. I want it be able to stay in my tool cabinet for months on end without draining the battery. Keeping the CPU powered and using its low power states just doesn’t cut it for something I plan to use only occasionally. My LPM is going to have a software controlled power switch. Some programmers do support a buffer where they will accept any voltage the target is using, but they require that the board you’re programming supplies the power. They will fry at 5 volts, which is what most programmers supply. So what makes my programmer so unique from what’s on the market that I felt compelled to design my own? Well let’s look at some of the features of my LPM design that make using standard programmers difficult. This, by the way, is how you know you truly have a hobby: When you’re building something that’s three levels deep from your actual goal you’ve entered the hobby domain.
I couldn’t find an ISP that did exactly what I wanted so I decided to build my own. To program small surface mount chips like the one I intend to use you need an ISP - an In System Programmer - which allows you to program (and reprogram) your finished circuit board. To program raw microcontrollers like this you need a chip programmer.
However, because I’m using the same chip family Arduinos use I can take advantage of Adafruit’s GFX or U8Glib and get a full drawing package for free.īut my new LPM design is not the point of this post either. That leaves a lot of manual work to create a drawing library, text rendering, font support, etc.
However, that just gets you the ability to render pixels. Reading the data sheet and writing code for this display’s SPI protocol is not rocket science.
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