Hardware

The TimeTagger4 is available as a PCIe plugin board (variant “–PCIe”) or as a desktop solution (variant “–TBT”). The two variants are shown in Figure 1.

Figure 1 Overview of the PCIe (left) and the TBT (right) variant of the TimeTagger4.

Installing the PCIe Board

The TimeTagger4 board can be installed in any PCIe-CEM slot with x1 or more lanes. Make sure that the PC is powered off and the main power connector is disconnected while installing the board.

Input and Connectors

Figure 2 shows the location on the inputs on the slot bracket. Figure 3 shows a side view of the PCIe variant of the TimeTagger4.

Figure 2 Input connectors of the TimeTagger4 on the PCIe bracket.

Figure 3 Schematic of the TimeTagger4 PCIe board. The connectors J12 and J25 are only present on Gen 1 boards.

LEMO-00 connectors are used for input connection. The inputs are AC-coupled and have an impedance of 50 Ω. A schematic of the input circuit is shown in Figure 4.

Figure 4 Input circuit of the TDC channels.

The digital threshold for each input can be adjusted individually to comply with a multitude of single-ended signaling standards (see timetagger4_configuration.dc_offset). The threshold can also be used to configure the input for either positive or negative pulses.

The connectors can also be used as outputs. DC-coupled output pulses for automatic internal triggering and control of external devices can be generated using the Timing Generators (TiGer).

The SMA connector at the top edge of the board can be used to connect an external 10 MHz clock signal. To enable use of an external clock, configure timetagger4_init_parameters.use_ext_clock accordingly.

Only Gen 1 TimeTagger4 boards have inter-board connectors near the top edge of the board. The pinout of connector J12 is shown in Table 2. The connector J12 is reserved for future use.

Table 2 Pinout of connector J12.

Pin	Name
1, 2	GND
3, 4	external CLK in N, external CLK in P
5, 6	GND
7, 8	reserved/NC
9, 10	GND
11, 12	reserved/NC
13, 14	GND
15, 16	reserved/NC
17, 18	GND
19, 20	reserved/NC
21, 22	GND
23, 24	reserved/NC
25, 26	GND
27, 28	reserved/NC
29, 30	GND
31, 32	reserved/NC
33, 34	GND

Status LEDs of the PCIe boards

Three status LEDs are present on the board, as seen in Figure 3.

• LED1 lights up red during the configuration of the FPGA and turns off afterward. If it stays permanently lit, the configuration failed.

• LED2 lights up green after the board is initialized by the driver and turns off when the device is closed by the software.

• LED3 lights up green when capture is started, yellow after the first start signal was detected and red when groups are missing.