I am looking to build an application that needs to display a QR code, and I want to minimize the cost of it.
I just need a preferably square display, capable of displaying a simple QR code with a short url, nothing more.
Can anyone recommend me something that is as cheap as possible? Thanks
Your objective may be resolved with a device known as an e-paper kit.
The one in the image above is 154 pixels square, qualifying for your low-resolution requirement. There are other sizes on the market, other resolutions and a wide range of costs. The one in the image is priced less than US$10.00. It's uncertain what you consider to be low-cost.
You should be able to find that you can purchase a processor such as an Arduino or Pi or adapt your current source to the product you select.
Amazon sells a hat for a Pi at a bit higher cost than the above device:
If your QR code is small enough (64x64 pixels max, so version 11) you can use an OLED display driven by a SSH1106 or SSD 1136. They can be controlled over I2C or SPI and don't draw a lot of power. Biggest drawback is that most are a bit small, maximum QR code size is 14.7x14.7 mm.
They sell for about US$2.50
