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‎.gitignore‎

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*.docx
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.vscode/

‎README.md‎

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[![Version: 1.0 Release](https://img.shields.io/badge/Version-1.0%20Release-green.svg)](https://github.com/0x007e/u3a) [![License CC By-NC-SA](https://img.shields.io/badge/Hardware-CC--BY--NC--SA--4.0-lightgrey)](https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode) ![Build](https://github.com/0x007e/u3a/actions/workflows/release.yml/badge.svg)
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# `U3A` - USB/UART/UPDI - Adapter
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The `U3A` project is based on a ([FT232](#additional-information)) that ist used as USB (Full Speed) to serial UART transceiver. Most signals of the ([FT232](#additional-information)) are routed to the connector pins `J2` and `J4`. Whithin the DIP switches the adapter can be switched from `UART` to `UPDI` mode to program microcontrollers. It is possible to select between two voltage sources. Either `5V` from USB or `3V3` from the internal LDO on the board.
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> The LDO itself can drive around `800 mA`. Therefore it is necessary to install a cooling unit inside the housing. The mount for this is already provided in the housing.
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| Experience | Level |
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|:------------|:-----:|
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| Soldering | ![?%](https://progress-bar.xyz/25?progress_color=00ff00&suffix=%20Low&width=120) |
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| Mechanical | ![?%](https://progress-bar.xyz/25?progress_color=00ff00&suffix=%20Low&width=120) |
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# Downloads
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| Type | File | Description |
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|:---------:|:------------------:|:-------------------------|
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| Schematic | [pdf](https://github.com/0x007E/u3a/releases/latest/download/schematic.pdf) / [cadlab](https://cadlab.io/project/29697/main/files) | Schematic files |
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| Board | [pdf](https://github.com/0x007E/u3a/releases/latest/download/pcb.pdf) / [cadlab](https://cadlab.io/project/29697/main/files) | Board file |
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| Drill | [pdf](https://github.com/0x007E/u3a/releases/latest/download/drill.pdf) | Drill file |
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| PCB | [zip](https://github.com/0x007E/u3a/releases/latest/download/kicad.zip) / [tar](https://github.com/0x007E/u3a/releases/latest/download/kicad.tar.gz) | KiCAD/Gerber/BoM/Drill files |
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| Mechanical | [zip](https://github.com/0x007E/u3a/releases/latest/download/freecad.zip) / [tar](https://github.com/0x007E/u3a/releases/latest/download/freecad.tar.gz) | FreeCAD/Housing and PCB (STEP) files |
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# Hardware
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There are two parts of the hardware. The pcb and the housing of the `U3A`. The pcb is created with [KiCAD](#additional-information) and the housing with `FreeCAD`. All files are built with `github actions` so that they are ready for a production environment. The housing is printed with a 3D-printer (`Dremel 3D40`).
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## PCB
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The circuit board is populated on both sides (Top, Bottom). The best way for soldering the `SMD` components is within a vapor phase soldering system and for the `THT` components with a standard soldering system.
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### Top Layer
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![Top Layer](https://github.com/0x007E/u3a/releases/latest/download/top.kicad.png)
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### Bottom Layer
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![Bottom Layer](https://github.com/0x007E/u3a/releases/latest/download/bottom.kicad.png)
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## Mechanical
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The housing has a tolerance of `0.2mm` on each side of the case. So the pcb should fit perfectly in the housing. The tolerance can be modified with `FreeCAD` in the `Parameter` Spreadsheet.
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### Assembled
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![Assembled](./images/assembled.png)
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#### Exploded
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![Exploded](./images/explosion.png)
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# Connection/Setup
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The `U3A` is powerd over USB with `5V`. The voltage of the pins can be setup through jumper `J1`. Either `5V` or `3V3`. The output of the system is driven by `CBUS4`. It needs to be configured through [FT_PROG](#additional-information). Mostly pins of the IC are routed to the connectors `J2` and `J4`
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## Simple loopback setup for testing purpose
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``` bash
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#
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# +-----------------------------------+ +---------------------+
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# |J2 U +---+---+ | |
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# +--+--+ S | USB |--+ +-----------------+ |
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# | VCC | B UPDI +---+---+ | | TeraTerm | |
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# | GND | / +---+---+ | | | ~~~~~~~~ | |
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# | PDI | U | | | | | | ~~~~~ | |
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# | CTS | A | | | | | | ~~~~~~~~~~~~ | |
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# L | RTS | R | X | X | | | | | |
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# O +---+ TXD | T +---+---+ +-+ | | +-----------------+ |
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# O +---+ RXD | / / / | | |
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# P +-----+ U +-+-+-+-+-+-+ | Computer |
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# B | P | 5V | 3V3 | | |
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# A | D +-----+-----+ +---------------------+
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# C | J2 I |
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# K | +---+---+---+---+---+---+---+---+ |
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# | | V | C | C | D | D | D | R | G | |
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# +-+ C | B | B | C | T | C | I | N +-+
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# | C | 3 | 2 | D | R | R | | D |
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# +---+---+---+---+---+---+---+---+
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```
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# Additional Information
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| Type | Link | Description |
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|:----------:|:--------------------------------------------------------------------:|:-----------------------------------------------------|
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| FT232RL | [pdf](https://ftdichip.com/wp-content/uploads/2020/08/DS_FT232R.pdf) | USB to serial UART interface IC |
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| FT_PROG | [web](https://ftdichip.com/utilities/#ft_prog) | EEPROM programming utility for use with FTDI devices |
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| KiCAD | [web](https://www.kicad.org/) | KiCAD project page |
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| FreeCAD | [web](https://www.freecad.org/) | FreeCAD project page |
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---
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R. GAECHTER

‎images/assembled.png‎

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‎images/explosion.png‎

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