VFAT readout electronics

A VFAT board from CERN is evaluated for use as a readout board to convert the GEM output analog signal to a digital signal.

LVDS
I2C

Breakout box specs (preliminary)

• 6 (or 8) inputs for ~1m ribbon cables from VFAT modules
• 3-bit DIP switch to select I2C address range for each VFAT
• Soft reset button for each VFAT?
• Hard reset button for each VFAT?
• Scan Mode switch
• ScanIn connector (cascaded)
• ScanOut connector (cascaded)
• ScanIn->ScanOut bypass for unconnected VFAT boards?
• RJ45 port to gumstix box containing I2C signals:
  • Power (3.3 or 2.5V)
  • Ground
  • SDA
  • SCL
• 34 pin ribbon connector for LVDS signals
• LEMO connector for LVDS trigger input
• LEMO connector for LVDS Master Clock
• I2C EPROM for testing?? (socketed)
• I2C expander(s) for status LEDs (socketed)
• Status LEDs:
  • Power (from I2C line)
  • I2C connect (flashing through I2C expand)
  • LVDS trigger status??
  • Power for each VFAT (feedback through common pins on VFAT board?)
  • I2C address ranges seen (0x0* - 0x8*)
• Some way to clear the UpsetReg (SEU counter) via button or 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