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.