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