feat: add mtca evm backplane input trigger db

[Insomnia1437]

Add backplane input related DB for mtca EVM, now EVM can use backplane input as trigger sources for

1. trigger events
2. DBus
3. Sequencer trigger

Verification sequences

generate 1 Hz test clock using EVR prescaler 0 and output to backplane 0

Hardware connection

MTCA-EVM-300 -> MTCA-EVR-300RF

backplane 0 as trigger source for EVM trigger events

# 1 Hz prescaler inside EVR
$ caget TT:MTCA-EVR-300:PS0Rate-I
TT:MTCA-EVR-300:PS0Rate-I      9.99994e-07

# use event 14 for test
$ caget TT:MTCA-EVM-300:TrigEvt0EvtCode-SP
TT:MTCA-EVM-300:TrigEvt0EvtCode-SP 14

# set EVM trigger event trigger source to backplane 0
$ caput TT:MTCA-EVM-300:TrigEvt0TrigSrc3-Sel 1
Old : TT:MTCA-EVM-300:TrigEvt0TrigSrc3-Sel Off
New : TT:MTCA-EVM-300:TrigEvt0TrigSrc3-Sel Back0

$ caget TT:MTCA-EVR-300:EvtE-SP.OUT
TT:MTCA-EVR-300:EvtE-SP.OUT    @OBJ=EVR,Code=14

$ caget TT:MTCA-EVR-300:EvtECnt-I
TT:MTCA-EVR-300:EvtECnt-I      0

# output 1 Hz clock to backplane 0
$ caput TT:MTCA-EVR-300:OutBack0SrcScale-SP 0
Old : TT:MTCA-EVR-300:OutBack0SrcScale-SP Prescaler 0
New : TT:MTCA-EVR-300:OutBack0SrcScale-SP Prescaler 0

$ caget TT:MTCA-EVR-300:OutBack0Src-RB
TT:MTCA-EVR-300:OutBack0Src-RB Prescaler 0

# event 14 received in 1 Hz
$ camonitor TT:MTCA-EVR-300:EvtECnt-I
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:24.516371 1
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:25.516392 2
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:26.516407 3
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:27.516429 4
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:28.516421 5
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:21:29.516471 6

---

backplane 0 as trigger source for EVM DBus0

# output 1 Hz clock to FP out0
$ caget TT:MTCA-EVR-300:OutFPUV0Src-RB
TT:MTCA-EVR-300:OutFPUV0Src-RB Prescaler 0

# output DBus0 to FP out1
$ caget TT:MTCA-EVR-300:OutFPUV1Src-RB
TT:MTCA-EVR-300:OutFPUV1Src-RB DBus 0

# output 1 Hz clock to Backplane out0
$ caget TT:MTCA-EVR-300:OutBack0Src-RB
TT:MTCA-EVR-300:OutBack0Src-RB Prescaler 0

# select DBus0 source to Backplane 0
$ caget TT:MTCA-EVM-300:Dbus0Src2-Sel
TT:MTCA-EVM-300:Dbus0Src2-Sel  Back0

verify FP0 and FP1 using oscilloscope

---

backplane 0 as trigger source for EVM sequencer trigger

$ caget -# 5 TT:MTCA-EVM-300:SoftSeq0EvtCode-SP
TT:MTCA-EVM-300:SoftSeq0EvtCode-SP 5 14 127 0 0 0

$ caget -# 5 TT:MTCA-EVM-300:SoftSeq0Timestamp-SP
TT:MTCA-EVM-300:SoftSeq0Timestamp-SP 5 10 0 0 0 0

$ caget TT:MTCA-EVM-300:SoftSeq0RunMode-Sel
TT:MTCA-EVM-300:SoftSeq0RunMode-Sel Normal

# set seq0 trig src to back0
$ caput TT:MTCA-EVM-300:SoftSeq0TrigSrc3-Sel 0
Old : TT:MTCA-EVM-300:SoftSeq0TrigSrc3-Sel Back0
New : TT:MTCA-EVM-300:SoftSeq0TrigSrc3-Sel Back0

$ caput TT:MTCA-EVM-300:SoftSeq0Commit-Cmd 1
Old : TT:MTCA-EVM-300:SoftSeq0Commit-Cmd Commit
New : TT:MTCA-EVM-300:SoftSeq0Commit-Cmd Commit

$ caget TT:MTCA-EVM-300:SoftSeq0TrigSrc-RB
TT:MTCA-EVM-300:SoftSeq0TrigSrc-RB Back0

$ caput TT:MTCA-EVM-300:SoftSeq0Load-Cmd 1
Old : TT:MTCA-EVM-300:SoftSeq0Load-Cmd 1
New : TT:MTCA-EVM-300:SoftSeq0Load-Cmd 1

$ caput TT:MTCA-EVM-300:SoftSeq0Enable-Cmd 1
Old : TT:MTCA-EVM-300:SoftSeq0Enable-Cmd 1
New : TT:MTCA-EVM-300:SoftSeq0Enable-Cmd 1

$ camonitor TT:MTCA-EVR-300:EvtECnt-I
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:22:16.517316 0
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:21.532507 1
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:22.532574 2
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:23.532546 3
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:24.532568 4
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:25.532548 5
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:26.532601 6
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:27.532642 7
TT:MTCA-EVR-300:EvtECnt-I      2026-05-25 17:36:28.532635 8

[jerzyjamroz]

@Insomnia1437, thank you for adding this missing part. It is also good that you tested it with the hardware. I have not checked all the .db processing details, so I trust your validation here.

My comment is about consistency.

Currently:

1. Trigger Events are assigned to Src3.
2. Sequencer Trigger Source is assigned to Src3.
3. The Distribute Bus part is mixed into Src2 together with Front2, Univ11, etc.

I think we should use Src3 consistently, and reserve it only for the Backplane inputs.

P.S.
I know that this DBus part looks like spaghetti in general, but it would be nice to make future changes cleaner.