Portable SDR using STM32F7-Discovery board and RTLSDR USB receiver.
We want to make a low-cost RF spectrum analyzer / receiver using an RTL-SDR compatible dongle connected to an STM32F7-Discovery board. The goal is to demonstrate the DSP capabilities of the STM32F7 processor and the usage of the USB Host Middleware in STM32 Cube to implement a custom class.
The project is developed using the free, Eclipse-based IDE called System Workbench for STM32 (SW4STM32). To set-up the IDE you should follow the instructions of the site. I used Eclipse Neon for C/C++ developers under Ubuntu 16.04.
- USBH driver is able to recognize and enumeate RTL-SDR
- Manipulating RTL2832 registers with USB Control Transfers working
- USBH driver was modifed to be able to deal with Stalled Control Transfers, that may arise while recognizing the RTL-SDR tuner chip by I2C.
- Tuner chip recognition (probing) is working.
- Elonics E4000 tuner driver is working.
- The data samples from RTLSDR are successfully copied to a SDRAM buffer.
- Use DMA for speeding up the data transfers from EP1 (samples)
- Perform some FFT on the samples to check what we are receiving.
- Check the correct operation of E4K_tune_freq
- Implement/Port other tuners from librtlsdr.
- STM32F7-Discovery Evaluation Board
- RTL-SDR compatible USB dongle
- Micro USB to USB OTG Adapter Cable (Look for in eBAY)
- External 5V power supply to STM32F7-Discovery.
- Linux standard build system (Make)
- GNU ARM Compiler Toolchain
- OpenOCD (properly patched for STM32F7)
The STM32F7-Discovery board connected to an RTL-SDR dongle was found to draw a total current of approximately 650mA. This is beyond the limit of current that can be provided by a standard USB 2.0 port (500mA). Therefore an external 5V power supply must be attached to JP2. In addition, the JP1 jumpers must be set as follows:
- JP1 5Vext: ON
- JP1 5Vlink: OFF
- JP1 USB_FS: OFF
- JP1 USB_HS: OFF
