Wall-E DIY Project with Wifi (Part 3)

After getting the display to work I started with the motors. In the left upper corner of the bread board you can see the motor controller I used. It is an L293D chip. It is basically a switch but you can control motor speed for a DC motor by using Pulse With Modulation (PWM). Basically switching on and off very fast. But I didn't use that at all. Only full on and off, but I had to move in two directions. The manufacturer of this Wall-E toy did something mechanically interesting. When the motor moves forward the head moves and when the motor runs backwards the arms move. With the L293D you can do this easily. You have a signal for direction and then it switches polarity for the power of the motor. I hooked the LD293 up with as less pins as possible since as you can see now I had to switch back to an ESP12 because I couldn't get the display driver stable on the ESP32 and I didn't want to spend a lot of time on figuring out why. So now I had the display working, the audio. Only thing left was the eyes and a led where I decided to go for single color in stead of  an RGB led. 

Then came the most complicated part. And I didn't really see that one coming. The display I bought was mounted on a small PCB. Between the display and the PCB is a very thing flat cable. I cut a small piece from the case so that I could stick the flat cable through that hole and stick the the display on the outside with thin double sided tape. But I couldn't reach in with my hand to attach the flat cable again and it was all very tight. After a couple of tries I got it, but then the display didn't work anymore :( I had put too much stress on the cable. So I killed the display :( I had to order a new one and bought a small flat cable extender in the process. After a week of waiting I could try again. This time I asked my girlfriend to help. And this time it worked :) So it did cost me an expensive display but I found a method to get it right.

After testing I concluded everything was OK for assembly. All electronics and software were tested. So I took a piece of universal development PCB with lots of holes and started soldering wires to it. This is a way to create a prototype PCB without actually designing and manufacturing a real PCB. I usually do this when I make something once. It is reliable and when you make a mistake it is easy to correct. So after assembling the PCB I tested everything again and it still worked. So time to assemble everything. More about that in the next part.