I'm fairly new to electronics and Arduino, but I am experienced with coding and programming.
My idea is to create a wrist strap (or more precisely a wrist strap bought from Amazon or somewhere) and have a screen and touch sensor that connects via bluetooth to an Android app.
So far, I have managed to use an Arduino Uno with a ST7789 and HC-05 to successfully send data from an Android app to the Arduino Uno via the HC-05 and display the message on the ST7789 display.
My problem is turning this into a portable project is deciding what board to use (Arduino Uno is one of the bigger ones and has header sockets which stick out and (I'm guessing) won't be a good idea for a small portable project.
Another problem I have is power supply. I have no idea of the different types of portable power devices and would require something small to not make the strap too bulky or have it attached to something.
I've attached photos of my idea and the current circuit (I haven't ordered the touch sensor yet), in case anyone had any suggestions.
Nice project. As Yo say, an UNO will not be part of the final solution. Use it as a door stop...
For system development it's likely good.
Do some Google about Arduino controllers and look at size as well appetite for current. That goes for the peripherals as well. You need to know the final current consumption before deciding for a certain battery.
To stay in the Arduino family: the Pro Mini 3.3V can run off a 3.7V LiPo with no issues (don't use the VIN pin, just connect straight to Vcc). Check the data sheet of your display, possibly it can run off a LiPo as well (i.e. voltage anywhere between 3.2 and 4.2V). That'd be the simplest.
Railroader:
Nice project. As Yo say, an UNO will not be part of the final solution. Use it as a door stop...
For system development it's likely good.
Do some Google about Arduino controllers and look at size as well appetite for current. That goes for the peripherals as well. You need to know the final current consumption before deciding for a certain battery.
Thank you.
I've had a look at the Arduino and the Pro Mini 3.3V looks the best (as someone after you suggested).
Probably a stupid question, but how did I find out the current consumption? Do I have to view the datasheets for each peripheral component?
wvmarle:
To stay in the Arduino family: the Pro Mini 3.3V can run off a 3.7V LiPo with no issues (don't use the VIN pin, just connect straight to Vcc). Check the data sheet of your display, possibly it can run off a LiPo as well (i.e. voltage anywhere between 3.2 and 4.2V). That'd be the simplest.
This is the datasheet for the display. The power/current consumption is on page 40 and I don't really understand what it means.
Probably a stupid question, but how did I find out the current consumption? Do I have to view the datasheets for each peripheral component?
Yes, that's the way to go, picking up the current data from the data sheet. Use the index starting on the second page! There You will quickly pick the proper page.
As I have four components (ST7789 display, HC-05 bluetooth, touch sensor, and LiPo battery) that need the VCC connection, how will I split/divide the power from the two VCC pinouts on the Arduino Pro Mini?
davechapperz:
As I have four components (ST7789 display, HC-05 bluetooth, touch sensor, and LiPo battery) that need the VCC connection, how will I split/divide the power from the two VCC pinouts on the Arduino Pro Mini?
Rather peculiar question!
You do not get power from the Pro Mini "Vcc" pin, you provide power to the Pro Mini that way. All these devices require power to be connected as your 3.7 V and ground from the battery. Basically, you may need to solder two wires to each connection pad/ hole on the Pro Mini and other modules.
You do not get power from the Pro Mini "Vcc" pin, you provide power to the Pro Mini that way. All these devices require power to be connected as your 3.7 V and ground from the battery. Basically, you may need to solder two wires to each connection pad/ hole on the Pro Mini and other modules.
Sorry, it was a newbie question!
So that I understand, I have to solder two wires to one hole (two to the VCC and two to the ground) and each wire will go to a different module (one for VCC and one for ground). Is this right?
That will be right. Your size constraint prevents you from using stripboard with multiple holes per strip as a mount for the Pro Mini so you will need some deft soldering!
Nearly done with the project and was about to stitch it together and then realised that if I do that then the battery would be tucked away with no access to charge it or unplug it. So I've thought of using a switch and a micro USB breakout board to change between charging the battery and using the battery to power the arduino board. As I'm new, I thought I'd post it on here to see if this would work.
Here is my crude drawing (red = VCC and blue = GND):
