Schematic¶
ESP32¶
There are two main options for our project. The first is the esp32, the second is the esp8266 with a bluetooth adapter. The bluetooth adapter takes up extra space, causing the whole device to be bigger than when a esp32 was used.
The esp32 is mainly chosen, because of its integrated bluetooth antenna. But the esp32 is also quicker and has more memory than the esp8266. Not only is the esp32 faster than the esp8266 its also a lot more efficient than the 8266, this is because the esp32 is a lot newer than the old esp8266.
Buttons¶
For the buttons, we chose tactile buttons because their size, feel, and especially the option to customize button caps make them the perfect choice.
We chose to use 5 buttons, because we need 4 for the Stephear app control, and the fifth button is for the voice assistant. The buttons are wired from data to ground, because this is a very simple and safe way to wire the buttons. After all the current only flows if the button is pressed.
Schematic Download¶
You can download the schematic here
PCB design¶
Button layout¶
We chose to place and function of the buttons in the same way Stephear did in their app, so it would be effortless to adapt to the new device.
The bottom button is used for the voice assistant and is placed under the four buttons, since its a very natural placement for your thumb, because its already near the four buttons all the time.
Single-sided¶
We chose to place the components on the same side. We chose this approach because it allows us to make the whole device allot thinner then if were to utilize a double sided pcb.
A single-sided would make the whole device a little taller, but this wouldn’t be a big problem because the cane is very long and thin so there is a lot of room for a long device.
zones and cutouts¶
Ground plane¶
We chose to use a ground plane because it improves the electrical characteristics of our circuit. It also simplifies the design of the device because it reduces the amount of traces needed. This results in a design that is a lot smaller.
antenna cutout¶
We chose to use a antenna cutout to reduce signal interference from the copper ground plane. Our cutout is a specific place on the backside of the pcb where there is no copper.
PCB Download¶
You can download the design here