Software defined radio on rpi zero
The goal of this project is to create a simple sdr using a rpi-zero and a simple hat. It should work to up to 150kHz, to be used as a ULF radio or bat detector.
contains a KiCad project for a hat for the rpi (zero). It contains a 1Mbit 16 bit spi adc, mcp33131 and a 14 bit dac, mcp4821. Also a preamplifier and lowpass filter.
Status: This is the design of the prototype. There still is one error in the PCB design. Pins 1 and 8 of the U4, a ths4521, should be swapped and a 100nF capacitor to ground should be connected to pin 2.
Kernel module to process the data from adc and dac. This also is work in progress. Currently I have not been able to get the FIQ interrupt working.
A variant of https://iosoft.blog/2020/11/16/streaming-analog-data-raspberry-pi/
The main changes for the 16 bit mcp33131 are:
- Used PWM to create the CNVST pulse.
- Writing dummy to create SCLK.
- added -U option to send data over UDP channel.
- DAC not used yet.
Basically works, but the data is partly wrong. Also the SPI clock should be lower than 5 MHz?