ZYNQ Time-to-digital converter

A fast high-resolution time-to-digital converter for the Red Pitaya Zynq-7010 SoC

Tested on Red Pitaya STEMLab 125-10 and STEMLab 125-14

Author: Michel Adamic ada.mic94@gmail.com

Performance
TDC core frequency: 350 MHz
No. of delay line taps: 192 (configurable)
Time resolution per channel: >11 ps
Accuracy: <10 ppm
DNL: -1 to +4.5 LSB
INL: +0.5 to +8.5 LSB
Measurement range: 47.9 ms
Dead time: ~14 ns
Max speed: ~70 MS/s

Included folders
AXITDC
TDC channel IP. Includes VHDL source files, test benches and customized Xilinx IP cores.

board
Red Pitaya board definition files.

figs
Various figures and schematics of the TDC design.

matlab

• TDCgui4.mlapp - MATLAB App Designer graphical user interface application.

setup
Files required to run the TDC system on the Red Pitaya board.

• TDCServer2.c - a Linux-based C program for the Zynq ARM core, which communicates with the TDC channels via the "mmap" system call. Addresses are set in the Address Editor of the TDCsystem project.
• PLclock script - contains bash commands for lowering the PL clock frequency from 125 to 100 MHz. Has to be executed before TDC implementation.
• TDCsystem_wrapper.bit - FPGA bitstream.

src
Source files for creating a two-channel TDC system example project.

2-channel TDC system example project

1. Open Vivado 2018.2
2. Using the Tcl Console, navigate to the "zynq_tdc/" folder and execute "source make_project.tcl"
3. Complete the synthesis & implementation steps

If you don't want to run these steps and create your own FPGA bitstream, you can use the one already provided in the setup folder.

Setup on the Red Pitaya system (STEMLab 125-10 or 125-14)

1. Copy the contents of the setup folder (FPGA bitstream, PLclock script and C server) on the Red Pitaya system
2. Run PLclock ("./PLclock") to lower the Zynq PL frequency to 100 MHz
3. Load the FPGA configuration ("cat TDCsystem_wrapper.bit > /dev/xdevcfg")
4. Compile and run the C server ("gcc -o TDCserver TDCserver2.c" and "./TDCserver")
5. On a client PC, start the MATLAB GUI application in Matlab App Designer to connect to the TDC system

TDC inputs are located on E1 extension connector pins 17 & 18 (connected to FPGA pins M14 & M15), voltage standard = LVCMOS33 (3,3 V). The TDCs are rising-edge sensitive, i.e. a timestamp is generated for each 0->1 transition.

Links
IEEE paper: https://ieeexplore.ieee.org/abstract/document/8904850
My thesis (in Slovene): https://repozitorij.uni-lj.si/IzpisGradiva.php?id=117846&lang=eng
Red Pitaya docs, schematics etc.: https://redpitaya.readthedocs.io/en/latest/