zeroSDR is an open source SDR receiver for Linux-based small screen embedded systems.
- Real-time spectrum and waterfall visualization
- Audio demodulation (FM/NFM/AM) with ALSA output
- Direct framebuffer rendering for minimal overhead
- Optimized for Raspberry Pi Zero 2W and Pi 5
- Designed for M5Stack Cardputer Zero (320x170 display)
- Raspberry Pi 5 or Pi Zero 2W
- RTL-SDR dongle (tested: RTL-SDR Blog V4, RTL2832U SDR)
- 320x170 SPI display on
/dev/fb0 - Latest rtl-sdr drivers (critical for correct frequency tuning)
sudo apt-get update
sudo apt-get install -y build-essential cmake librtlsdr-dev libasound2-devmkdir build && cd build
cmake ..
make -j$(nproc)
sudo make installzerosdr # Start with defaults
zerosdr -f 100000000 # Tune to 100 MHz (FM broadcast)
zerosdr -f 118000000 # Tune to 118 MHz (aviation AM)
zerosdr -s 2048000 -g 20 # Custom sample rate and gain| Key | Action |
|---|---|
← → |
Tune ±100 kHz (hold for acceleration) |
Shift+← Shift+→ |
Tune ±1 MHz (hold for acceleration) |
0-9 . |
Direct frequency input (MHz) |
Enter |
Confirm frequency input |
Backspace |
Delete last digit |
Esc |
Cancel frequency input |
| Key | Action |
|---|---|
Shift+Z |
Cycle display zoom (3.2M → 2.8M → ... → 50k) |
Shift+R |
Cycle FFT resolution (256/512/1024/2048) |
M |
Cycle display mode (spectrum+waterfall / spectrum / waterfall) |
Shift+S |
Take screenshot (saved to ~/zerosdr_*.png) |
| Key | Action |
|---|---|
D |
Cycle demodulation mode (FM → NFM → AM) |
Shift+B |
Cycle demodulation bandwidth |
Space |
Toggle audio on/off |
V / C |
Volume up / down |
S |
Adjust squelch (+5% per press) |
S (long press) |
Reset squelch to 0% |
A |
Toggle audio AGC on/off |
| Key | Action |
|---|---|
G |
Toggle hardware AGC on/off |
↑ / ↓ |
Manual gain ±1 dB (when AGC off) |
| Key | Action |
|---|---|
+ / - |
Cycle sample rate (1.024/1.2/1.8/2.048/2.4 MHz) |
Q / Esc |
Quit |
- 200 kHz: Narrow (crowded bands)
- 250 kHz: Standard stereo
- 300 kHz: Default (full stereo + RDS)
- 400 kHz: Wide (strong signals)
- 500 kHz: Maximum (best quality)
- 6.25 kHz: Ultra-narrow
- 12.5 kHz: Default (standard NFM)
- 25 kHz: Wide NFM
- 5 kHz: Narrow
- 10 kHz: Default (standard AM)
- 15 kHz: Wide
Press Shift+Z through zoom levels (from wide to narrow):
- 3.2 MHz: Full spectrum view
- 2.8 MHz / 2 MHz: Wide view
- 1 MHz / 500 kHz: Medium zoom
- 200 kHz / 100 kHz: Narrow zoom
- 50 kHz: Ultra-narrow (maximum resolution)
Usage: zerosd -k <device> Set keyboard input device (default: auto-detect)
-h Show help
If the displayed spectrum doesn't match the actual frequency:
- Update rtl-sdr drivers to the latest version (most common cause)
- Check PPM correction with
rtl_test
lsusb | grep RTL # Verify device is connectedlitysudo usermod -a -G video $USER
# Log out and back inaplay -l # List audio devices
alsamixer # Check volume levels# Install toolchain
sudo apt-get install -y gcc-aarch64-linux-gnu g++-aarch64-linux-gnu
# Build
mkdir build-zero2w && cd build-zero2w
cmake .. \
-DCMAKE_SYSTEM_NAME=Linux \
-DCMAKE_SYSTEM_PROCESSOR=aarch64 \
-DCMAKE_C_COMPILER=aarch64-linux-gnu-gcc \
-DCMAKE_CXX_COMPILER=aarch64-linux-gnu-g++
make -j$(nproc)
# Copy to device
scp zerosdr pi@cardputer-zero.local:/home/pi/This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for det Feng**
- Email: bestedwin@gmail.com
- Built with rtl-sdr library
- Designed for M5Stack Cardputer Zero