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README.md

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 # pynvcm
+
+pynvcm with friends is a tool to program the NVCM of a Tillitis' Tkey
+(ICE40).
+
+Either clone this repository and run from the Python interpreter or
+download and run our pre-packed executables from
+[releases](https://github.com/tillitis/pynvcm/releases).
+
+**Note**: programming the NVCM is non-reversiable.
+
+**Note**: the NVCM can still be read out unless you set the security
+bit.
+
+## Usage
+
+Set up a python virtualenv, unless if you are using the pre-packed
+executables you can skip this step.
+
+For linux
+```
+sudo apt install python3.10-venv
+python3 -m venv venv
+source venv/bin/activate
+pip install -r requirements.txt
+```
+
+for macOS
+
+```
+brew install python3.10
+python3 -m venv venv
+source venv/bin/activate
+pip install -r requirements.txt
+```
+
+for Windows
+```
+winget install Python.Python.3.10
+python3 -m venv venv
+source venv/bin/activate
+pip install -r requirements.txt
+```
+
+then run with the appropriate options
+
+```
+usage: pynvcm.py [-h] [-v] [-f] [-b] [--speed SPI_SPEED] [-i] [--read READ_FILE] [--verify VERIFY_FILE] [--write WRITE_FILE] [--ignore-blank] [--secure]
+                 [--my-design-is-good-enough]
+
+options:
+  -h, --help            show this help message and exit
+  -v, --verbose         Show debug information and serial read/writes
+  -f, --sleep_flash     Put an attached SPI flash chip in deep sleep
+  -b, --boot            Deassert the reset line to allow the FPGA to boot
+  --speed SPI_SPEED     SPI clock speed, in MHz
+  -i, --info            Read chip ID, trim and other info
+  --read READ_FILE      Read contents of NVCM
+  --verify VERIFY_FILE  Verify the contents of NVCM
+  --write WRITE_FILE    bitstream file to write to NVCM (warning: not reversable!)
+  --ignore-blank        Proceed even if the chip is not blank
+  --secure              Set security bits to prevent modification (warning: not reversable!)
+  --my-design-is-good-enough
+                        Enable the dangerous commands --write and --secure
+```
+
+For example to write the NVCM, verify and set the security bit use:
+
+```
+./pynvcm.py --my-design-is-good-enough --write application_fpga.bin --verify application_fpga.bin --ignore-blank --secure
+```
+
+## Licenses and SPDX tags
+
+Unless otherwise noted, the project sources are licensed under the
+terms and conditions of the "GNU General Public License v2.0 only":
+
+> Copyright Tillitis AB.
+>
+> These programs are free software: you can redistribute it and/or
+> modify it under the terms of the GNU General Public License as
+> published by the Free Software Foundation, version 2 only.
+>
+> These programs are distributed in the hope that they will be useful,
+> but WITHOUT ANY WARRANTY; without even the implied warranty of
+> MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+> General Public License for more details.
+>
+> You should have received a copy of the GNU General Public License
+> along with this program. If not, see:
+>
+> https://www.gnu.org/licenses
+
+See [LICENSE](LICENSE) for the full GPLv2-only license text.
+
+External source code we have imported are isolated in their own
+directories. They may be released under other licenses. This is noted
+with a similar `LICENSE` file in every directory containing imported
+sources.
+
+The project uses single-line references to Unique License Identifiers
+as defined by the Linux Foundation's [SPDX project](https://spdx.org/)
+on its own source files, but not necessarily imported files. The line
+in each individual source file identifies the license applicable to
+that file.
+
+The current set of valid, predefined SPDX identifiers can be found on
+the SPDX License List at:
+
+https://spdx.org/licenses/