Pico-Backscatter

An educational project on backscatter using Raspberry Pi Pico

--> Updates <--

• 08.05.2023: Comment about the baud-rate: Notice that the baud-rate of the CC1352 is specified from 20-1000 kBaud (we tested it working as low as 30 kBaud with the backscatter setup). The CC2500 would allow for lower baud-rate configurations (specified down-to 1.2 kBaud). The timing of the state-machine is precise (no significant error or clock-difference needs to be considered).
• 27.04.2023: The Python script (generating the PIO) generated state machines which did not compile due to a mistake by splitting the required delay over a number of instructions. The issue has been resolved. The C-implementation was not affected by this issue.
• 29.03.2023: We added a new library project_pico_libs/backscatter.c. The baseband example demonstrates how to generate a PIO-file (python script) and assemble it using pioasm. This has the disadvantage that testing different baseband settings require a re-compilation for each setting. Therefore, we implemented a automatic generation of the state-machine binary in C (project_pico_libs/backscatter.c) and demonstrate its use in carrier-receiver-baseband. This enables changing the baseband settings on-the-fly for a convenient automation of tests.

Repo Organization

• hardware contains the hardware design with further description and explanation (generating the PIO using the python script).
• project_pico_libs contains the libs for all projects using the RPI Pico (carrier/receiver/baseband).
• baseband contains a 2-FSK baseband code using Pico PIO together with a generator script, its description and some exercise questions.
• carrier-CC2500 contains a carrier generator using the Mikroe-1435 (CC2500) on the Pico.
• receiver-CC2500 contains a receiver using the Mikroe-1435 (CC2500) on the Pico.
• carrier-Firefly contains the configuration guidance for home setup with zolertia firefly as carrier.
• carrier-characteristics contains a measurement to estimate the typical carrier bandwidth.
• carrier_receiver-CC1352 contains the configuration guidance for lab setup with CC1352 as carrier and/or receiver.
• carrier-receiver-baseband integrates all components into one setup: the Pico generates the baseband, uses one Mikroe-1435 (CC2500) to generate a carrier and a second Mikroe-1435 (CC2500) to receive the backscattered signal. This setup generates the state-machine code at run-time, such that the baseband settings can be changed without re-compilation.
• stats contains the system evaluation script.

Installation

A number of pre-requisites are needed to work with this repo: Raspberry Pi Pico SDK, cmake and arm-none-eabi-gcc have to be installed for building and flashing the application code.
Please follow the installation guidance in Getting started with Rasberry Pi Pico.
Using Visual Studio Code is recommended.