# MTA1-USB PCB designs

## Boards

The KiCad board projects all follow this directory structure:

| Path | Description |
| ---  | --- |
| /project | KiCad 6 project |
| /project/gerbers | PCB release files |
| /project/test | Scripts / gateware used for production tests |

### mta1-usb-v1

![](../../doc/images/mta1-usb-v1.jpg)

This is the first production version of the MTA1-USB design.

Main features:
* Miniaturized hardware the size of a small USB stick.
* The Interface FPGA from the MTA1-USB-DEV design has been replaced with an Interface MCU running a USB-to-Serial converter firmware. This was done to ease development of the FPGA design.
* A touch sensor IC is provided instead of the switch for user presence detection.
* Test pads are provided on the bottom of the board for programming the SPI flash, and also for measuring extra GPIO pins. The 'MTA1-USB-V1-Programmer' board is designed to support this.

### mta1-usb-v1-programmer

![](../../doc/images/mta1-usb-v1-programmer.jpg)

This is a programming jig for the mta1-usb-v1 board.

### mta1-usb-dev

![](../../doc/images/mta1-usb-dev.jpg)

This is the original design, intended as a development platform. It is a larger PCB, that connects to a PC via a USB C cable. 

Main features:
* 2 ICE40 FPGAs.
* The first ICE40 (Interface FPGA) is connected to a USB C plug, and is loaded with a gateware that contains a soft USB device. This gateware acts as an USB-to-GPIO interface to the second ICE40.
* The second ICE40 (application FPGA) is loaded with a RISC-V soft core containing the security firmware. User applications are run on this gateware.
* The second ICE40 also has an input button for user presenence detection.
* An FTDI module is included for programming both the Application and Interface FPGAs.
* Both ICE40s can be configured to boot from included SPI flash memories, NVCM, or be live programmed from the FTDI module.
* All GPIO lines between the two FPGAs, as well as all programming signals, are exposed on 0.1" headers for probing.

## Libraries

### mta1-library

This is a shared KiCad library for all boards in the project.

### KiCad-RP Pico

This is a KiCad library for the Raspberry Pi Pico symbol and footprint. It was extracted from the [Kicad-RP-Pico](https://github.com/ncarandini/KiCad-RP-Pico) project. It is licensed under the [Creative Commons CC-BY-SA 4.0 License](https://creativecommons.org/licenses/by-sa/4.0/legalcode), with an exception exempting waving any control of derived works.