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# TTL to/from Blocking level converter
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# Project Description
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The Blocking converter is a system which converts TTL pulses to Blocking
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ones and it is able to replicate the later ones. The system consists of
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two VME64x double height boards: a front one and a rear one. The front
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board holds all the active circuitry, whereas the rear board is passive
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and targeted for connectivity. By dividing the functionality of each
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board in this way, an improvement can be achieved in terms of ease of
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maintenance.
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The TTL to blocking converter is a system designed to replicate TTL and
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blocking pulses. An incoming TTL pulse is replicated simultaneously on
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both the TTL and blocking channel on which it was received. The reverse
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also holds true, i.e., a blocking pulse on an input channel gets
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repeated on both the TTL and blocking outputs of the respective channel.
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The system consists of two VME64x double height boards, the front module
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and the rear transition module (RTM). The front module contains all the
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active circuitry, whereas the RTM is passive and targeted for
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connectivity.
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[![](/uploads/e1ee42fca69ff9a6683c7b8d67cc6361/convTTLblo_front_small.jpg)](/uploads/a66c7768842968e12a324a5e8eaceb0c/convTTLblo_front.jpg)
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[![](/uploads/ba6714d0bde37544fcd74e4514a43c77/convTTLblo_top_small.jpg)](/uploads/a896326313ea75fea7db0930a8e11677/convTTLblo_top.jpg)
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fp-top-bot.png
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## How does it work?
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A block diagram with the main functionalities carried out by the pulse
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converter system is shown below.
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BLOschema.png
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When a pulse is received either in the front panel (TTL level) or the
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rear one (Blocking level), the event is time-tagged in the FPGA and a
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Blocking pulse is outputted in the rear panel. Then, the information
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about the events received in the FPGA can be accessed through the I2C
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pins in the VME64x J1 connector.
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## Features
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## Main Features
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- VME64x double-height form factor using Front and Rear Transition
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Module
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- The output pulse is a CERN level standard, [Standard
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Blocking](https://www.ohwr.org/project/conv-ttl-blo/uploads/8ba57dff4f18540c947830f70e8c8ead/BlockingSpecification.pdf).
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- 6 conversion channels. Every channel has:
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- A TTL input at the front panel.
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- A TTL output at the front panel.
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- A Blocking input at the rear panel.
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- Three Blocking outputs at the rear panel.
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- Additional 4 TTL inverter channels at the front panel.
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- LEMO 00 connectors at both front and rear panels.
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- Galvanic isolation on the Blocking outputs.
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- A TTL input at the front panel;
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- A TTL output at the front panel;
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- A blocking input at the rear panel;
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- Three blocking outputs at the rear panel;
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- Additional 4 INV-TTL channels at the front panel;
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- LEMO 00 connectors at both front and rear panels;
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- Galvanic isolation on the blocking outputs;
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- Rear panel: input protection against high-current and high-voltage
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transients.
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- Communication through I2C on the VME bus allows to fetch logs of the
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repetitor board and change the pulse width.
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- Time-tagging: [White-Rabbit
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capable](https://www.ohwr.org/project/white-rabbit)
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- FPGA firmware can be remotely upgradeable.
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transients;
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- Communication through I2C on the VME bus for various control
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purposes;
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- *Provisioned*: time-tagging via
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[White-Rabbit](https://www.ohwr.org/project/white-rabbit);
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- *Provisioned*: Remote upgrade of FPGA firmware via I2C protocol
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- LEDs in panels:
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- One LED for every channel. Front and rear panels.
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- Three LEDs for White Rabbit status. Front panel.
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- Power and general error LEDs. Front panel.
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- [RTM Detection](RTM-board-detection) and classification tables.
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- One LED for every channel, front and rear panels;
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- Various status LEDs on the front panel (White Rabbit, multicast,
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power, error, etc.);
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- [RTM Detection](RTM-board-detection)..
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## Documents
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