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| == TTC Output Signals == {{attachment:LeCroy7.png}} |
TTCM
Front Panel Interface
|
TTC Bus Output
TTC bus output provides clock, spill, trigger and reset LVDS signals. It is compatible with VMEDAQ specification.
LEDs
- 1 (red) - lights on spill when data readout is enabled
- 2 (yellow) - blinks on blocked triggers (dead time)
- 3 (green) - blinks on triggers being read out
Inputs
- NIM1..NIM7 - Trigger inputs, NIM standard, 5 ns minimum
- SPILL - external sync signal, positive logic. Readout enabled with logic one on this input.
- LVDS1..LVDS32 - Trigger inputs, LVDS or ECL, 5 ns minimum
Outputs
- OUT1 - NIM, spill output
- OUT2 - NIM, BRIC clock
- P12 internal connector - aux. TTC output
TTCM VME Interrupt Lines
- IRQ1 - data read XOFF input
- IRQ2 - spill output
- IRQ5 - data read request output
VME Registers
Detailed description of TTCM VME Registers
VME Data Format
Trigger Cable
For use with TQDC-16, special ribbon twisted pair cable is supplied with 34-pin connector on one side and four 10-pin connectors on other side. One cable connects four TQDC-16 modules with TTCM.
Input Aggregation
Trigger inputs are combined after shaping and delay by OR scheme. 40 inputs are reduced to 4 trigger lines. Logic OR is performed this way (trigger line = input OR input ...):
- ST = LVDS1
- TQDC1 = LVDS6 | LVDS10 | LVDS14
- TQDC2 = LVDS18 | LVDS22 | LVDS26 | LVDS30
- NIM = NIM1 | ... | NIM7
Trigger Logic Delay
Measured delay from NIM input to TTC bus output: min. 530 ns, max. 580 ns. Due to 20 MHz sampling the delay is varied by 50 ns. this applies to TTCM firmware 1.0.10604
TTC Bus
TTC connector pinout
pin pair |
signal |
description |
1, 2 |
spill |
Trigger and data readout enable |
3, 4 |
parity |
Odd parity of spill and trigger signals |
5, 6 |
trigger |
Trigger signal |
7, 8 |
clock |
41.667 MHz clock signal |
9, 10 |
ground |
TTC bus signal ground |
Even signal pin positive.
Spill, trigger and parity signals have width 50 ns and are synchronous to clock.
Connector: 2.54 mm 2x5 (10 pins).
Connector part numbers: AMP - 1658621-1
Signal Timing
measurement |
min |
typ |
max |
|
clock frequency |
|
41.666667 MHz ±0.001% |
|
|
spill, parity, trigger |
setup time, ns |
|
8.5 |
10.0 |
hold time, ns |
5.0 |
6.0 |
|
|
Timing provided by design TTCM v2.0 firmware rev.8512
1 ns step
CLK ___/^^^^^^^^^\_________/^^^^^^^^^\_________/^^^
TRIG ________XXXXXXX^^^^^^^^^^^^^XXXXXXX__________...
| setup |hold|
TTC 2.0 Timecode Extension
Spill signal is used as a gate for data acquisition. Trigger signal is used only when spill signal is active.
In order to provide TAI timecode to modules an extension of TTC standard is proposed, TTC 2.0.
With spill signal low, trigger line become an encoded serial data channel, 40 Mbps data rate. Timecode information is transmitted serially using 8b10b encoding and K28.5 comma symbol as idle code. Big endian byte order. A sequence of data coded forms a frame.
TAI timecode is encoded as TAI 64-bit Timestamp.
Frame Type 1: Timecode
Frame type 1 transmission time: 25 ns * 20 words * 10 bit = 5 µs. The moment of beginning of first bit of frame corresponds to TAI timecode data being transferred.
Byte |
|
0 |
Frame type |
1 |
TAI seconds [39:32] |
2 |
TAI seconds [31:24] |
3 |
TAI seconds [23:16] |
4 |
TAI seconds [15:8] |
5 |
TAI seconds [7:0] |
6 |
TAI nanoseconds [29:22] |
7 |
TAI nanoseconds [21:14] |
8 |
TAI nanoseconds [13:6] |
9 |
TAI nanoseconds [5:0], flags[1:0] |
10 |
spill_id[31:24] |
11 |
spill_id[23:16] |
12 |
spill_id[15:8] |
13 |
spill_id[7:0] |
14 |
reserved |
15 |
reserved |
16 |
CRC32[31:24] |
17 |
CRC32[23:16] |
18 |
CRC32[15:8] |
19 |
CRC32[7:0] |
- TAI - International Atomic Time
- flags[3:0] = {time_valid, ptp_wr_mode, ptp_mode, ntp_mode}
- CRC32 use Ethernet 802.3 polinom
P12 TTC Connector
Internal P12 connector is duplicating the front-panel TTC output. Even signal pin positive.
pin pair |
signal |
description |
1-10 |
reserved |
don't use |
11, 12 |
trigger |
trigger signal |
13, 14 |
spill |
Trigger and data readout enable |
19, 20 |
ground |
signal ground |
TTCM Block Diagram
TTC Output Signals
