The ALICE trigger electronics

The ALICE trigger system (TRG) consists of a Central Trigger Processor (CTP) and up to 24 Local Trigger Units (LTU) for each sub-detector. The CTP receives and processes trigger signals from trigger detectors and the outputs from the CTP are 3 levels of hardware triggers: L0, L1 and L2. The 24 sub-detectors are dynamically partitioned in up to 6 independent clusters. The trigger information is propagated through the LTUs to the Front-end electronics (FEE) of each sub-detector via LVDS cables and optical fibres. The trigger information sent from LTU to FEE can be monitored online for possible errors using the newly developed TTCit board. After testing and commissioning of the trigger system itself on the surface, the ALICE trigger electronics has been installed and tested in the experimental cavern with appropriate ALICE experimental software. Testing the Alice trigger system with detectors on the surface and in the experimental cavern in parallel is progressing very well. Currently one setup is used for testing on the surface; another is installed in experimental cavern. This paper describes the current status of ALICE trigger electronics, online error trigger monitoring and appropriate software for this electronics.