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CM4/CM5 Flash Jig

The CM4/CM5 Flash Jig is a production fixture for flashing Raspberry Pi Compute Module 5 modules through board test points. It is designed for teams that need to program multiple modules reliably without repeatedly using the 100-pin mezzanine connectors, carrier boards, or fragile manual cabling.

The jig combines mechanical alignment, pogo-pin contact, controlled power, USB boot handling, status indication, and automated flashing into one repeatable operator workflow.

CM5 Flash Jig with a Compute Module installed

What It Is For

Use this jig when you need to:

  • prepare CM5 eMMC modules in small-batch or production workflows;
  • reduce manual handling and avoid repeated use of the Compute Module mezzanine connectors;
  • make the flashing process repeatable for operators;
  • catch basic electrical or boot issues before a module leaves the station;
  • keep traceable records for each flashed module.

Key Features

  • Automated stand self-test before production starts.
  • Image flashing to CM5 eMMC through Raspberry Pi USB boot mode.
  • Power rail and total DUT current measurement during the cycle.
  • Boot check after flashing.
  • Built-in display for simple operator guidance.
  • HardPy web interface for detailed progress, measurements, logs, and failure reasons.
  • Local database and StandCloud report storage.

System Overview

The complete stand is organized around a few functional blocks:

Block Role
Host controller Raspberry Pi. Runs the stand self-test and the main HardPy cycle, including flashing, measurements, and boot checks.
Mechanical fixture with pogo pins Eloprint BAL jig. Positions the Compute Module, holds it in a repeatable operator-safe position, and contacts the required CM5 test points without using the mezzanine connectors.
Power and measurement subsystem Supplies controlled power to the DUT and measures key electrical parameters during the cycle.
Operator interface Shows simple production states on the built-in display and provides a detailed HardPy web interface for live test information.
Reporting and data storage Saves measured values, boot logs, and final results to the local database and StandCloud.

The built-in display is enough for routine production work: the operator can follow READY, FLASHING, PASS, and FAIL states directly on the jig. For detailed progress, measurements, logs, and failure reasons, the HardPy interface can be opened in a browser from any device on the same network as the host Raspberry Pi.

Physical Specifications

Parameter Value
Overall dimensions 140 x 115 x 180 mm
Mass 520 g

How It Works

Before production starts, the stand runs a self-test to confirm that the host, fixture controls, measurement path, display, and required tools are ready. After the stand reaches READY, each DUT follows the main HardPy cycle:

  1. The operator places a CM5 module into the jig.
  2. Closing the lid aligns the module and brings the pogo pins into contact with the required test points.
  3. The host Raspberry Pi holds nRPIBOOT low and powers the module.
  4. The stand measures the module power rails and the total DUT current consumption.
  5. rpiboot starts the Compute Module in USB mass-storage mode.
  6. The host detects the DUT eMMC as a block device.
  7. The selected image is written to the eMMC.
  8. The fixture powers the module down, releases boot mode, and can perform a boot/status check.
  9. The display and software report a final PASS or FAIL result.
  10. All measured values, boot logs, and test results are saved into a report in the local database and StandCloud.

Operator Workflow

The normal production cycle is intentionally short:

  1. Wait for READY.
  2. Insert the Compute Module.
  3. Close the jig lid.
  4. Wait while the HardPy cycle flashes and verifies the module.
  5. Read PASS or FAIL.
  6. Open the lid and remove the module.
  7. Start the next unit.

For normal operation, the front-panel display provides the required operator guidance. When more detail is needed, an engineer or technician can open the HardPy web interface in a browser on a laptop, tablet, or phone connected to the same local network.

Compatibility

Module Status Notes
Raspberry Pi Compute Module 5 with eMMC Supported target The jig is designed around the CM5 test points used for power, USB boot, UART, and status signals.
Raspberry Pi Compute Module 4 with eMMC Validation pending The relevant test points appear to be in compatible positions, but full CM4 compatibility must be confirmed by testing before it is treated as supported.

Safety Notes

  • Make sure the CM5 is correctly aligned before closing the jig.
  • Do not open the jig or remove the CM5 during flashing or testing. Wait until the display shows PASS or FAIL.
  • Flashing erases the data already stored on the CM5 eMMC.