By building my own onboard UART to USB converter and using SMD, I was able to make a relatively small device.
As always, comments and constructive criticisme are very much appreciated.
Step 1: What do you need?
- An attiny2313 (datasheet)
- A FT232RL Uart to USB converter (datasheet)
- A Mini USB B connector
- 3 x Kingbright DC-10EWA Ledbar(datasheet)
- 10 x 150Ohm resistor
- A ferrite bead
- 2 x 100nF capacitor
- A 10nF capacitor
- A 4.7uF capacitor
- A 6pin female header
- Materials to make a PCB or some veroboard
- A Programmer and compiler of your choice
To run the python script on your pc, you will need:
As always, you can use thru-hole components instead of smd parts.
Step 2: The circuit
There are 2 connections from the FT232RL to the attiny2313: RX and TX (actually we need only The TX of the FT2313RL to the RX of attiny but connecting both lines makes debugging the microcontroller a lot easier).
The 3 ledbars are multiplexed. Their cathodes are connected to Port B, PortD.5 and PortD.6. The anodes are connected to Portd.2 - 4.
Miso, Mosi, SCK and Reset are connected to the header for programming together with VCC and GND.