= TDC Raw Data Format =

Hardware: [[MTDC-64]], [[TDC-96]], [[PhTDC]]

See also: [[VmeDaqRawdataFormat|VME DAQ Rawdata Format]]

Data read out of the TDC is contained in 32 bit data packets. The first four bits of a packet are used to define the type of data packet. The following 4 bits are used to identify the ID of the TDC chip (programmable) generating the data. Only 8 out of the possible 16 packet types are defined for TDC data (bit 31 always set to zero by TDC). The remaining 8 packet types are added by higher levels of the DAQ system.

||<-2 rowclass="bits">Data types||
||0|| ||
||1|| ||
||2||TDC header||
||3||TDC trailer||
||4||TDC leading edge time measurement||
||5||TDC trailing edge time measurement||
||6||TDC error||
||7||Padding (ignore it)||

||<-32 rowclass="bits">2 - TDC event header||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>2||<:-4>TDC ID||<:-12>event number||<:-12>TDC timestamp||

TDC ID is the programmed ID of TDC

TDC timestamp in number of 25 ns time intervals since global trigger timestamp found in event header.

||<-32 rowclass="bits">3 - TDC event trailer||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>3||<:-4>TDC ID||<:-12>event number||<:-12>TDC word count||

Time measurement data format depends on resolution set.

||<-32 rowclass="bits">4, 5 - Single edge measurements (normal resolution, 19 bits)||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>4/5||<:-4>TDC ID||<:-5>channel||<:-19>time measurement ||
 . data type: 4 - leading, 5 - trailing.
 . channel - TDC channel number, 0 to 31
 . time measurement - leading or trailing edge measurement in programmed time resolution

||<-32 rowclass="bits">4, 5 - Single edge measurements (25 ps, very high resolution, 21 bits)||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>4/5||<:-4>TDC ID||<:-3>channel/4||<:-2>time bits [1:0]||<:-19>time bits [20:2] ||
 . data type: 4 - leading, 5 - trailing.
 . channel/4 - TDC channel number, 0 to 7 (should be multiplied by 4)

||<-32 rowclass="bits">4, 5 - Combined leading and trailing measurement, pairing mode (not used in VMEDAQ)||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>4/5||<:-4>TDC ID||<:-5>channel||<:-7>width||<:-12>leading time||

 . width - pulse width in programmed time resolution
 . leading time - leading edge measurement in programmed time resolution

||<-32 rowclass="bits">6 - TDC error||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>6||<:-4>TDC ID||<:-9>reserved||<:-15>TDC error flags||

TDC error flags bits:
 . [0] Hit lost in group 0 from read-out fifo overflow
 . [1] Hit lost in group 0 from L1 buffer overflow
 . [2] Hit error have been detected in group 0
 . [3] Hit lost in group 1 from read-out fifo overflow
 . [4] Hit lost in group 1 from L1 buffer overflow
 . [5] Hit error have been detected in group 1
 . [6] Hit lost in group 2 from read-out fifo overflow
 . [7] Hit lost in group 2 from L1 buffer overflow
 . [8] Hit error have been detected in group 2
 . [9] Hit lost in group 3 from read-out fifo overflow
 . [10] Hit lost in group 3 from L1 buffer overflow
 . [11] Hit error have been detected in group 3
 . [12] Hits rejected because of programmed event size limit
 . [13] Event lost (trigger FIFO ovefrlow)
 . [14] Internal fatal chip error has been detected

Most important error bits are 12 and 13. Error bit 14 should be ignored.

For detailed description of TDC please refer to [[http://tdc.web.cern.ch/tdc/hptdc/docs/hptdc_manual_ver2.2.pdf|HPTDC manual]].

||<-32 rowclass="bits">7 - Padding||
||31||30||29||28||27||26||25||24||23||22||21||20||19||18||17||16||15||14||13||12||11||10||9||8||7||6||5||4||3||2||1||0||
||<:-4>7||<:-28>0||

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[[CategoryRawData|RawData]]