Custom made carrier board bring up - Verdin IMX8M plus

Technical Support
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Hi Team,

We have made a custom carrier board in a form factor compatible to our system with reference from Mallow carrier board. We are using IMX8M plus verdin SoM.

I have powered on the custom carrier board and the independent power rails are up. The filtered supplies and 5V rails are powered perfectly.

While the SoM is connected, the system is stuck in reset mode and I suspect boot is not completed

Observations are :

  1. CTRL_RESET_MOCI# - Low

  2. CTRL_PWR_EN_MOCI – L ow

  3. Reset LED is glowing red.

Since the Mallow reference board and our custom carrier board behaves same when SoM is not connected, I couldn’t identify the root cause of this issue. The SoM works fine in Mallow carrier board.

Can you please help me with this.

Thanks,
Preethi

2

Hi, I’m the Toradex AI Assistant.

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(1)

Hi Preethi,

Based on your observations, the Verdin iMX8M Plus is stuck in reset, preventing proper boot. Let me help you troubleshoot this issue systematically.

Understanding the Power Management Signals

The signals you’re observing indicate specific states in the power-up sequence (1):

  • CTRL_RESET_MOCI# (Pin 258): Reset output for carrier board peripherals, derived from the SoC reset (1)
  • CTRL_PWR_EN_MOCI (Pin 254): Enable signal for carrier board peripheral power rails (1)

Power-Up Sequence Analysis

The Verdin iMX8M Plus features the NXP PCA9450C power management IC (PMIC) that manages the power-up sequence (1). When main power is applied, the PMIC should:

  1. Ramp up all rails
  2. Release the POR_B signal at the end
  3. Make CTRL_RESET_MOCI# available as a buffered output (1)

Key Areas to Check

1. Power Input Requirements

Verify your main power supply meets specifications (1):

  • VCC pins (251, 253, 255, 257, 259): 3.135V to 5.5V main power supply
  • Use proper decoupling capacitors on the carrier board

2. Critical Control Signals

Check these power management pins (1):

  • CTRL_RESET_MICO# (Pin 260): Should have 100k pull-up to 1.8V SNVS rail. Can be left floating if not used
  • CTRL_PWR_BTN_MICO# (Pin 248): Should have 100k pull-up to 1.8V SNVS rail. Can be left floating
  • CTRL_RECOVERY_MICO# (Pin 246): Should have 10k pull-up. Can be left floating

3. Ground Connections

Ensure all ground pins are properly connected (1):

  • Multiple GND pins (10, 11, 18, 27, 28, 33, 39, 40, 45, 50, 51, 65, 68, 71, 77, 83, 86, 89, 97, 98, 103, 109, 110, 115, 121, 122, 127, 134, 145, 146, 158, 167, 170, 173, 179, 182, 194, 195, 204, 209, 223, 224, 229, 230, 236, 242, 243)

Troubleshooting Steps

  1. Measure VCC Rails: Verify 3.135V-5.5V on all VCC pins
  2. Check Pull-up Resistors: Ensure proper pull-ups on control signals
  3. Verify Ground Integrity: Check continuity on all ground connections
  4. Compare with Mallow: Double-check your schematic against the Mallow reference design
  5. Power Sequencing: Use an oscilloscope to verify the power-up sequence timing

Recovery Mode Test

Try entering recovery mode to isolate the issue (2):

  • Pull CTRL_RECOVERY_MICO# (pin 246) low during power-on
  • This should force the module into USB serial loader mode

Since your SoM works fine on the Mallow board, the issue is likely in the carrier board power management or critical signal routing.

Best regards,
Toradex AI Assistant.

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