VFAT readout electronics
VFAT readout Block Diagram
A VFAT board from CERN is evaluated for use as a readout board to convert the GEM output analog signal to a digital signal.
VFAT Board specifications
Signals
LVDS Signals to I/I module using 40 pin ribbon cable
I2C signals
Breakout box specs (preliminary)
The breakoutbox is a circuit board with no active elements that separates the I2C command signal lines from the LVDS data I/O lines. The box is designed to support 6 VFAT readout cards. The box is being design to be mounted on the detector rotator. All 6 VFAT cards will have their signal lines go into the break out box. The I2C lines will then go our of the breakout box along an RJ45 standard ethernet cable. The LVDS lines will exit though a standard 40 pin ribbon cable.
- 6 inputs for ~1m ribbon cables from VFAT modules
- 3-bit DIP switch to select I2C address range for each VFAT
- Soft reset for each VFAT controlled via I2C expander chip
- Shared hard reset line from Gumstix
- Scan Mode switch
- ScanIn connector (cascaded)
- ScanOut connector (cascaded)
- RJ45 port to gumstix box containing I2C and other signals:
- Power (3.3 or 2.5V)
- Ground
- SDA
- SCL
- Hard Reset
- Extra line for Link detection
- 34 pin ribbon connector for LVDS signals
- LEMO connector for LVDS trigger input
- LEMO connector for LVDS Master Clock
- I2C expander(s) for status LEDs (socketed)
- Status LEDs:
- Power (from I2C line)
- I2C connect (flashing through I2C expand)
- Power for each VFAT (feedback through common pins on VFAT board?)
- Hard Reset LED
- Clear UpsetReg (SEU counter) via I2C expand
Ribbon cable pinouts
| # | Name | Value | Test rig color Primary/Second |
| B1 | DGND | Digital Ground | Black/Grey (shared) |
| A1 | DVDD | +2.5V | Red/Grey (shared) |
| B2 | SDA | I2C Data | Green/Yellow |
| A2 | SCL | I2C Clock | Yellow/Green |
| B3 | DGND | Digital Ground | Black/Grey (shared) |
| A3 | DVDD | +2.5V | Red/Grey (shared) |
| B4 | |||
| A4 | |||
| B5 | I2C ADDR 2 | I2C Address Most | White/Blue |
| A5 | I2C ADDR 1 | I2C Address Middle | White/Orange |
| B6 | I2C ADDR 0 | I2C Address Least | White/Green |
| A6 | REH-S | Soft Reset (Program saved) | White/Grey |
| B7 | |||
| A7 | REH-B | Hard Reset | Grey/White |
| .............. | |||
|---|---|---|---|
| B22 | DGND | Digital Ground?? | |
| A22 | SCAN E | ||
| B23 | AGND | Analog Ground | |
| A23 | AVDD | 2.5V | Grey/Red |
| B24 | AGND | Analog Ground | |
| A24 | AVDD | 2.5V | Grey/Red |
| B25 | AGNDD | Analog Ground?? | Grey/Black |
| A25 | AVDD | 2.5V | Grey/Red |
The PC board-mount socket for the cable is ERNI 154765 for reel or ERNI 063197 for tube packaging.
The cable crimp-ons are ERNI 024403 or premade cables 300mm long are ERNI 173795