Thomas Kolb
2cedcb712a
This change controls a GPIO on the expansion connector depending on the surrounding temperature. If external temperature is too low for charging, the GPIO is set high, else it is set low. In combination with the new LNSC-2420-Addon board this allows to switch on a high-power heater connected directly to the solar panels whenever the temperature is too low to charge the battery. Once the temperature becomes high enough again, the heater is switched off and the battery is charged instead. |
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doc | ||
fxplib@896464ee67 | ||
ldscripts | ||
libopencm3@c82c7406aa | ||
oocd | ||
src | ||
utils | ||
.gitignore | ||
.gitmodules | ||
compile_flags.txt | ||
LICENSE | ||
Makefile | ||
README.md |
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.