I updated the picture in the manual with a current picture of a Rev5.1 board, and also added a picture of the bottom side. If you need a picture without the blue labels, have a look at https://www.psi.ch/drs/old-evaluation-boards at the bottom.
Here is the explanation of the optional components:
- R1, C2, R6, R29, R30 and same components for other channels: Normally the board is AC-coupled. You can make the board DC-coupled by briding C1, C9, C13, removing R6, C2, adding R1, adding R29, removing R30. The CAL signal then enters before the THS4508. We found that DC coupling gives slightly higher noise and is prone to high input DC levels, so we ship the board usually AC-coupled.
- R84 & Co. defines the hysteresis of the trigger comparators as described in the schematics
- R99-R106, R143: If soldered, the board is configured in cascading mode with 4 channels @ 2048 bins. R143 tells the FPGA that we are in this mode, so the firmware can correctly configure the DRS4
- R118 & Co. defines the MCX output level to be either 3.3V or 5V (default)
- R146-R149 connect JTAG to the uC. We planned at one point to make firmware upgrades through USB, but we never implemented that, so these resistors are not soldered.
I hope I covered everything. If I overlooked any optional component please tell me.
I'm troubleshooting a board which uses the DRS4 and adopts an analog front end very similar to the evaluation board. As a result, we rely on the eval board as a reference. In doing so we've encountered an issue in the manual:
The high resolution photo in Figure 1. is useful, but it seems to correspond to an older version of the board. For instance, the RF switch can't correspond to the schematics of Rev5.1 in the appendix.
Request: Could the manual be updated with a high resolution image of Rev5.1. Also, could a high resolution of the bottom side of the board be included in the manual? This is desirable since it has the version number and contact information, so it will remove any ambiguity about what board you're looking at and what schematics you should refer to.
A second question, which might be overly broad: what is the impact of installing the optional components (marked * in the schematics) on the analog front end? Why are a lot of these left uninstalled on the eval board?