Two cameras introduce a scheduling problem as well as a bandwidth problem. For LFE5U-45F-8BG381C, define how both input streams share processing, storage and the host connection before selecting interfaces. A second sensor does not merely double a pin list: different clocks, frame timing and backpressure can change the architecture.
Engineering reference updated October 19, 2026. Suggested checks and calculated budgets below are not reported board measurements.
Calculate the aggregate stream first
Assume two independent 1,920 × 1,080 cameras, each producing 30 frames per second at 10 packed bits per pixel. Excluding blanking and protocol overhead, one camera generates 622.08 Mb/s, so the pair produces 1,244.16 Mb/s. That active-image payload already exceeds the nominal line rate of a single 1 Gb/s Ethernet connection. A larger FIFO cannot remove a sustained rate deficit.
If the host expects each sample expanded into a 16-bit container, the two-camera payload becomes 1,990.656 Mb/s before headers or padding. Keep packed sensor format, internal representation and host format as separate entries in the budget. Cropping, reducing frame rate or compressing changes the result, but each choice also changes the application's output.
For a hypothetical 16-bit host bus transferring one word on each cycle at 100 MHz, the raw ceiling is 1.6 Gb/s. That is below the 1.990656 Gb/s container-format demand even before turnaround and idle cycles. This is an arithmetic interface example, not a verified 100 MHz capability for this FPGA, package or receiving device.
Distinguish line storage from complete frames
The 45F provides 1,944 kb of embedded block memory in 108 blocks. Interpreting k as 1,024 gives a raw ceiling of 248,832 bytes. A single 1,920 × 1,080 image at 10 packed bits needs 2,592,000 bytes, and a synchronized pair needs 5,184,000 bytes. Full-frame storage therefore requires a different memory strategy or a smaller data representation.
By contrast, three lines for each camera at the same packed width require 2 × 3 × 1,920 × 10 = 115,200 bits, or 14,400 raw bytes. That is a candidate line-buffer allocation, subject to memory width, ports and block packing. It leaves other demands to budget separately: input queues, clock-domain crossings, metadata and host stalls.
At the combined packed active-payload rate, a 1 ms host pause accumulates 155,520 bytes if both streams continue. This simplified result excludes burst timing, blanking and internal format expansion. Even a short pause can consume much of the raw EBR pool. Define how much storage is actually allocated to that queue and how overflow is reported or prevented.
Synchronize meaning as well as data
Decide whether the application requires simultaneous exposure, approximate frame pairing or merely independent streams. A shared output queue does not synchronize exposure. Carry camera identity, frame identifiers and any required timestamps through the pipeline so that host software can detect missing or mismatched frames.
For independent clocks, use a coherent transfer architecture with suitable FIFO and reset behavior. Specify what happens when one camera stops or restarts: a design that waits indefinitely for a pair can stall the surviving stream. Set a timeout or explicit recovery policy appropriate to the application, and make dropped frames observable.
Respect the exact 45F interface boundary
LFE5U-45F-8BG381C has 44K LUTs, 72 dedicated 18 × 18 multipliers, 203 BG381 user I/O and no embedded multi-gigabit SERDES. CSI-2/D-PHY reception needs a separately verified electrical and protocol solution. A PCIe or SGMII link cannot be obtained simply by enabling a transceiver in this LFE5U device. Select a supported external interface, bridge or different FPGA architecture according to the complete system requirement.
Use the 45F pinout to reserve clocks, configuration pins, bank supplies and the host interface before committing the PCB. A dual-camera design does not automatically fit because a resource table lists enough LUTs. Synthesize the actual receive, processing and arbitration logic, then examine mapping and routed timing.
BG381 is a 381-ball caBGA with a 17 × 17 mm body and 0.8 mm pitch. The commercial code specifies 0°C to +85°C junction operation. VCC is 1.1 V nominal within 1.045–1.155 V, and VCCAUX is 2.5 V nominal within 2.375–2.625 V. Determine VCCIO by the selected standards. Plan boot from an appropriate external configuration source and check the hardware checklist rather than assuming a universal rail order or a fixed flash size.
Acceptance questions for the system
Exercise unequal frame arrival, a stalled host, a camera restart and the maximum intended stream format. Check that identity and boundaries survive every transfer and that overflow counters reflect intentional stress. Compare measured sustained service rate and queue occupancy with the assumptions above when the board exists. The calculations here establish planning limits; they are not a completed dual-camera implementation or a measured throughput claim.
When discussing replacement material, specify LFE5U-45F-8BG381C, quantity and required lot documentation. Ask for the offered part marking, date/lot identification, packaging condition and agreed inspection scope. A symptom, a visual marking check or a successful JTAG identification does not certify authenticity or grade. Availability, delivery and any documentation commitments require confirmation for the actual offer.
Manufacturer references
- ECP5 and ECP5-5G Family Data Sheet, FPGA-DS-02012-3.4, September 2025: device resources, operating conditions, power-up, configuration, pin summaries and ordering information.
- ECP5 and ECP5-5G Hardware Checklist, FPGA-TN-02038-2.1, September 2025: power delivery, configuration signals, bank supplies and board connections.
- Density-specific ECP5U pinout: use the BG381 package column.
- ECP5 documentation directory: configuration, software and migration resources.