Troubleshooting¶

Symptoms you may see while bringing up a PF1550, their causes and the fix for each, cheapest check first.

Start with GetErrorFlags() after a failing call: DeviceNotFound or I2cRead / I2cWrite point at the bus, WrongDeviceId at the device, InvalidParam at the arguments, ProfileApply at a write the chip refused.

The chip does not answer¶

Symptom	Cause	Fix
`EnsureInitialized()` fails with `DeviceNotFound`	No ACK at 0x08	Check the pull-ups to VDDIO, SDA and SCL not swapped, a common ground
Same, and the SDK logs an address of 0x10	8-bit address passed to a 7-bit API	Pass 0x08; shift only inside your port if the SDK wants it
Same, on a programmed part	OTP selects another address (0x09 to 0x0F)	Scan the bus and pass the address to the constructor
`WrongDeviceId`	Another device answers at 0x08, or DEVICE_ID is not 0x7C	Read `ReadDeviceId()`; a PF1500 reads 0x78
Errors at high bus speed	Clock above 400 kHz, or edges faster than 20 ns	Run at 400 kHz or less; lower the master's drive strength
The ESP32 example reports no device	Nothing wired, or the wrong pins	Expected without hardware; otherwise check Kconfig `PF1550_I2C_SDA_GPIO` / `SCL_GPIO`

Writes do not change the rails¶

Symptom	Cause	Fix
`SetSwVoltage()` / `SetSwVoltageMv()` return `false`	SW3, or an SW1 / SW2 declared DVS-disabled: those voltage registers are read-only. Or the voltage is off the DVS grid	Change the set point in OTP, or declare DVS with `SetSwDvsEnabled()` if the part has it (Rails and OTP)
A rail reads far below the expected voltage	A DVS-disabled code written with `WriteRegister()` to a DVS-enabled SW1 / SW2 (0x07 is 0.6875 V there)	Use `SetSwVoltageMv()`; declare the mode with `SetSwDvsEnabled()`
A profile change has no effect after a reset	The PMIC kept the previous values: an MCU reset does not reset it	Power the PMIC down completely, then apply the profile again
The snapshot shows the old values after a profile	The profile stopped at a failed write	Check the return value and `ProfileApply`; the writes before it did happen
`SetVbusCurrentLimitMa()` returns `false`	The value is not 10, 100, 500, 1000 or 1500 mA	Write `VBUS_INLIM_CNFG` with `code << 3` for other Table 58 values

Board symptoms (Portenta H7 and carriers)¶

Symptom	Cause	Fix
Carrier +3V3 or JTAG VTref is 0 V while the processor runs	SW2 is off; with the default profile it also turns off in STANDBY	Apply the carrier profile (`SW2_CTRL = 0x0F`)
LDO outputs are dead but the processor runs	The LDO inputs hang off SW1, which is not up yet	Use the carrier profile: SW1 first, then a 5 ms wait
USB does not enumerate after boot	USB_VBUS_EN / USB_OTG_EN low, or STANDBY high	`SetPowerMode(PowerMode::Run)` and `SetUsbRails(true, true)` before USB starts
The rails drop when the board idles	STANDBY asserted, and the rail's `STBY_EN` bit is clear	Drive STANDBY low, or set `kStbyEn` in the rail's control register

Faults and self-test¶

Symptom	Cause	Fix
A fault comes back right after `ClearLatchedFaults()`	The cause is still there	Read the SENSE register for the live state
INTB never goes low	Every interrupt is masked (the reset value)	`SetInterruptMaskAll(false)`, or unmask one group

What software cannot check¶

Measure the rails, VBUS / OTG behaviour on USB-C and the I2C waveforms under load with instruments; the snapshot reports set points and status bits, not voltages.