Sync Box DC-in io

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MCE0 to MCE7

8 Fibre outputs. Carries a 50 MHz Manchester-encoded signal containing data packets, which include incremented sequence numbers. Programmable as two sets of 4 outputs with differently spaced data packets on each.

RS232 Command IO

DB9 connector (CJ2), TTL input and output, used to command the Sync Box from a PC using a regular RS232 cable.

TTL-IN

BNC connector (CJ5), TTL input, spare input to the FPGA. ***Not currently used, and open for suggestions.

TTL-OUT

BNC connector (CJ6), TTL output. Carries a 50 MHz clock signal.

Power

Circular connector (CP1), 5V input.

Interface Connector: CJ3

A DB25 connector that provides the following auxiliary input/outputs:

DATA_VALID

Differential RS485 input. Detects falling edges from a Real-Time Sequencer (implemented by SCUBA2) which tells the Sync box when to tell the MCE's to collect data.

DATA_SYNC1 (formerly DV_SPARE1)

differential RS485 output. Carries a 5 MHz clock signal that is synchronous with DATA_SYNC2. (WARNING: signal polarity may be swapped)

DATA_SYNC2 (formerly DV_SPARE2)

differential RS485 output. Carries a 5 MHz data signal that is synchronized with DATA_SYNC1, and contains the same frame sequence numbers as the MCE(0-7) outputs. NOTE: This output only contains the DV info stream (40-bit), but not the occurrences of Addr_Return-to-Zero between DVs. (WARNING: signal polarity may be swapped)

DATA_SYNC3

output, available both as TTL and differential RS485, asserted for 1us on an Address-Return-to-Zero(ARZ) if a DV pulse is detected since the last ARZ.

DATA_SYNC4

output, available both as TTL and differential RS485, asserted for 1us on an Address-Return-to-Zero(ARZ) if a DV pulse is detected since the last ARZ.

Pinout

Pin	Signal	Pin	Signal
1	Data_Valid+	14	GND
2	Data_Valid-	15	Data_Sync1+
3	GND	16	Data_Sync1-
4	Data_Sync2+	17	GND
5	Data_Sync2-	18	Data_Sync3+
6	GND	19	Data_Sync3-
7	Data_Sync3_TTL	20	GND
8	GND	21	Data_Sync4+
9	Data_Sync4_TTL	22	Data_Sync4-
10	N/C	23	GND
11	N/C	24	N/C
12	N/C	25	N/C
13	N/C

Schematics

• Connector Pinout
• Block Diagram
• Sync Board Schematics

Notes

Here are examples of RS485 driver/receiver chips:

• Quad Differential Receiver SN75LBC173D
• Differential Driver/Receiver pair SN75179B