Table 41. Board bring-up checklist (continued)
Checklist Item Details Owner
Findings
and Status
(on a bypass capacitor). This reveals any IR drops on the board that
could cause issues later. Ideally, all of the i.MX8 voltage rails should be
checked, but see the guidance below for important rails to check for the
i.MX8 QM and i.MX8 QXP.
i.MX8 QM - VDD_SNVS, VDD_MAIN, VDD_A53, VDD_A72,
VDD_DDR_CH0, VDD_DDR_CH1, VDD_ANA_1P8 (SCU_1V8) and
VDD_MAIN are particularly important voltages and they must fall within
the parameters provided in the i.MX8 data sheet.
i.MX8 QXP - VDD_SNVS, VDD_MAIN, VDD_A35, VDD_DDR,
VDD_ANA_1P8 (SCU_1V8) and VDD_MAIN are particularly important
voltages and they must fall within the parameters provided in the i.MX8
data sheet.
Verify that all voltage supplies meet required ripple tolerances under full
load conditions.
3. Verify the power-up
sequence.
Verify that power on reset (POR_B) is de-asserted (high) after all power
rails have come up and are stable. See the i.MX8 data sheet for details
about power-up sequencing.
4. Measure/probe input
clocks (32.768 kHz, 24 MHz,
and others).
Without proper clocks, the i.MX8 will not function correctly.
5. Check the JTAG
connectivity.
This is one of the most fundamental and basic access points to the
i.MX8 to allow the debug and execution of low level code and probe/
access the processor memory.
Note: The following items may be worked on in parallel with other bring-up tasks.
Access the internal RAM.
Verify the basic operation of the i.MX8 in the system. The on-chip
internal RAM starts at address 0x0090 0000 and its size is 256 KB.
Perform a basic test by performing a write-read-verify to the internal
RAM. No software initialization is required to access the internal RAM.
Verify CLKO outputs
(measure and verify default
clock frequencies for desired
clock output options) if the
board design supports the
probing of clock output balls.
This ensures that the corresponding clock and the PLLs are working.
Note that this step requires chip initialization (for example, via the JTAG
debugger) to properly set up the IOMUX to output clocks to I/O balls and
to set up the clock control module to output the desired clock. See the
chip reference manual for more details.
Measure boot mode
frequencies. Set the boot
mode switch for each boot
mode and measure the
This verifies the specified signals’ connectivity between the i.MX
8QM/QXP and the boot device and that the boot mode signals are
properly set. See the System Boot chapter in the chip reference manual
for details about configuring the various
Table continues on the next page...
NXP Semiconductors
Avoiding board bring-up problems
i.MX8 QM / i.MX8 QXP Hardware Developer’s Guide, Rev. 2.4p, 06/2021
User's Guide 84 / 89
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