VTP Streaming Configuration System

CODA 3.0 VTP/FADC streaming readout with automatic pedestal generation and dynamic configuration file management.

Overview

This system automatically generates FADC pedestals and creates runtime configuration files during the CODA download transition. It separates user-defined configuration parameters from runtime-generated configurations, ensuring proper ordering and parameter propagation.

Architecture

Configuration Flow

User Config (input)
    ↓
Parse ALL parameters (VME + VTP)
    ↓
Validate required parameters
    ↓
Generate pedestals (fadc250peds)
    ↓
Generate runtime configs:
  - vme_<rocname>.cnf (VME/FADC settings + pedestals)
  - vtp_<rocname>.cnf (VTP streaming settings + dynamic payload enable)
    ↓
Use generated configs for runtime configuration

Generated File Naming Convention

Two runtime configuration files are created during the download transition. Their names are built from <rocname>, which is the short hostname of the ROC (e.g. test2).

File	Pattern	Example
VME / FADC config	vme_<rocname>.cnf	vme_test2.cnf
VTP config	vtp_<rocname>.cnf	vtp_test2.cnf

Both files are written into the directory given by $CODA_CONFIG.

How <rocname> is determined — producer vs consumer:

• Producer (fadc_master_stream_vg.c): reads <rocname> from the first line of the pedestals file ($CODA_DATA/<hostname>_peds.txt). That line has the format FADC250_CRATE <rocname>, where <rocname> is the short hostname written by fadc250peds.

• Consumer (vtp_stream3_1udp_vg.c): derives the same value independently at runtime by calling gethostname() and then (1) stripping any trailing whitespace/newlines, (2) removing the domain suffix (everything from the first . onward), and (3) replacing any remaining non-alphanumeric characters (other than _ and -) with _.

The two sides must agree. As long as the short hostname reported by the kernel matches the FADC250_CRATE value in the pedestals file, the consumer will find the file the producer created.

Key Design Choices

1. Parse Before Generate

• User config is parsed FIRST to extract all VME and VTP parameters
• All required parameters are validated before any file generation
• Ensures consistency and catches configuration errors early

2. Single Source of Truth

• All configuration parameters defined in user config file (config/userConfig.txt)
• No hardcoded values in runtime configuration generation
• Changes to user config automatically propagate to generated files

3. Generated Files for Runtime

• FADC configured using generated $CODA_CONFIG/vme_<rocname>.cnf
• VTP configured using generated $CODA_CONFIG/vtp_<rocname>.cnf
• User config is input only; runtime uses generated files

4. Dynamic Payload Configuration

• VTP payload ports configured based on VTP_PAYLOAD_EN from config
• VTP_PAYLOAD_EN dynamically generated from active FADC slots in pedestals
• Slot-to-payload translation ensures correct mapping

5. Correct ppmask Accumulation

• Payload mask (ppmask) accumulated across ALL active payloads using |= operator
• Ensures streaming event builder receives data from all configured payloads
• Critical for proper event synchronization

Files

Configuration

• config/userConfig.txt - User-defined configuration (VME + VTP parameters)
• $CODA_CONFIG/vme_<rocname>.cnf - Generated FADC config (runtime)
• $CODA_CONFIG/vtp_<rocname>.cnf - Generated VTP config (runtime)
• $CODA_DATA/<hostname>_peds.txt - Generated pedestals

Readout Lists

• vme_rol/fadc_master_stream_vg.c - FADC master ROL with config generation
• rol/vtp_stream3_1udp_vg.c - VTP streaming ROL with dynamic payload config

Libraries

• vtp/vtpLib.{h,c} - VTP hardware interface
• vtp/vtpConfig.{h,c} - VTP configuration parsing with streaming parameters
• fadc250/fadc250Config.{h,c} - FADC configuration parsing

Usage

Environment Setup

export CODA=/path/to/coda
export CODA_DATA=/path/to/data
export CODA_CONFIG=/path/to/config

Configuration File

Create user config based on config/userConfig.txt template:

# VME/FADC parameters
FADC250_MODE 1
FADC250_W_OFFSET 1200
FADC250_DAC 3270
...

# VTP parameters
VTP_STREAMING_ROCID 0
VTP_STREAMING_DESTIP 129.57.177.25
VTP_STREAMING_MAC 0xCE 0xBA 0xF0 0x03 0x00 0x9d
...

Build

cd vme_rol && make fadc_master_stream_vg.so
cd ../rol && make vtp_stream3_1udp_vg.so

Run

Point CODA run control to your user config file. During download transition:

1. System parses user config and validates parameters
2. Executes fadc250peds to generate pedestals
3. Creates vme_<rocname>.cnf and vtp_<rocname>.cnf in $CODA_CONFIG
4. FADC and VTP configured using generated files

Key Features

• Automatic pedestal generation during download transition
• Dynamic payload configuration based on active FADC slots
• Parameter validation catches missing/invalid config early
• Comprehensive logging shows which files are used at each phase
• Fallback support for VTP if generated config missing
• ROC name discovery from pedestal file format

Requirements

• CODA 3.0 framework
• fadc250peds tool in $CODA/linuxvme/fadc-peds/
• VTP firmware: streamingv3 with EJFAT support
• FADC250 modules in VME crate

Version

VTP v3.10.2 with streaming configuration system