When I started to dig into USB topic it was quite a surprise, the amount of efforts the smart people around the world put into it just unbelievable. Even more fascinating fact – it actually worked out. The excitement reached some saturation when I realized the prices (: Vendor ID will cost you 5 grands per year, want to use a USB logo – no problem, just add another 6 grands on the top. Now we could test the compliance of your device with our standard for n grands… The companies using USB are listed on the website www.usb.org (USB Implementers Forum – USB-IF). The curious one could just count a number of companies and calculate the profit just from the year subscription, and this thing is going on for a long long time already. Well they have definitely built an addictive stuff. I, personally, have found the usage for my projects a bit excessive, I definitely not ready to put 5 grands per year for USB in the cheap humidity sensor.
Now, there are tons of different information, it is really challenging to grasp all at once, I will be honest and won’t pretend that I got everything, have a lot of holes in the knowledge, I just need to make it alive and respond to my commands. So, what I gonna to do is to show the info which looked important to me and then will conduct two experiments on this “foundation”.
Sometimes the cleanest way to design a nice readable schematic in Proteus is to create a separate model with its own graphical symbol with pins attached to this model, not the fastest way but a kind of proper approach within a normal working process.
I was interested in the encoder as you may know, which is not available in the standard proteus component library, starting from a simple drawing of the symbol I would like to use at higher levels:
After I had enough time playing with a thermal sensor DS18b20 and the RTC DS1307 I decided to bundle them together into a single device. Another reason was the fact that the cheap Chinese clock called a day and let its electronic soul leave the nice enclosure. I considered this as an opportunity to put my stuff inside of it.
That is what I got in the end:
+1 reason is that I had a free sample of the “port expander” PCA9539, I mentioned this IC in experiment #13.