Added README and LICENSE documents

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Thomas Kolb 2021-06-12 18:40:36 +02:00
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The MIT License (MIT)
Copyright (c) 2021 Thomas Kolb (cfr34k)
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# Firmware for the LNSC-2420 Solar Charger
The LNSC-2420 is a PWM-based solar charge regulator for 24 V systems supporting
up to 20 A charging current.
Noteworthy features:
- High-side switching with N-Channel MOSFETs:
- Gate voltage is provided by a charge pump which doubles the battery
voltage.
- The MOSFETs are controlled using GPIOs.
- Current and voltage measurement:
- The solar current, load current, solar voltage, battery voltage and charge
pump output voltage are measured using the internal ADC of the STM32F030.
- Low power usage:
- The charge pump is disabled if both power FETs are off.
- Additionally, the microcontroller is put into deep sleep (Stop Mode) if no
solar power is available and the battery voltage is in undervoltage
protection.
- LED status display:
- 6 LEDs show the internal charging and discharging state.
- The LEDs are controlled using Charlieplexing (i.e. only 3 GPIOs are needed)
- Protections:
- Solar panel reverse current
- Battery overvoltage
- Battery undervoltage
- Load current limit
## Calibration
The sensing hardware should be quite accurate, but some minor error always
remains. They can be compensated via the parameters in `src/calibration.h`.
To adjust those parameters, first set all `CAL_FACTOR`s to 1000, recompile and
flash the firmware. Then watch the RS485 output, which contains all
measurements in a line starting with `MEAS`. Apply a known current/voltage for
each measurement and calculate:
Actual value
CAL_FACTOR = 1000 * -----------------------
Value shown by firmware
Round to the nearest integer and replace the 1000 in `src/calibration.h` by the
calculated value.
## Customization
All customizable parameters can be adjusted in `src/config.h`.
## License
The code in this repository (except submodules) is licensed under the [MIT license](LICENSE).