Troubleshooting

Symptoms you may see while bringing up a BMP581, their causes and the fix for each, cheapest check first.

Start with the DriverError of the failing call (ToString(r.error)): Bus and NotInitialized are transport problems; the others mean the chip answered but did not confirm a step.

Init() fails

Error	Cause	Fix
NotInitialized	Your port's EnsureInitialized() returned false	Install or open the bus before Init()
Bus	No acknowledge at the address, or a dead bus	Address from SDO (0x46 low, 0x47 high), pull-ups to VDDIO, CSB tied to VDDIO for I2C
InvalidChipId	Another part at that address, SDO floating, or an SPI port without kInterface, read before SPI was selected	Check the address; on SPI declare kInterface = Interface::Spi (Porting)
NvmNotReady	The NVM had not loaded, or nvm_err is set	Init() already soft-resets once when STATUS reads 0. Wait at least 2 ms (t_powup) after power-up; if it persists, the part is faulty
NvmCommandError	nvm_cmd_err left over from an earlier NVM command	Soft reset, then Init() again

SoftReset() fails

Error	Cause	Fix
Bus	A read after the reset failed (the missing ACK of the reset command itself is expected and accepted over I2C), or an SPI port failed to send the command	The same wiring checks as for Init()
InvalidChipId	CHIP_ID read 0 after the reset: the chip did not come back, or (SPI) the port declares Interface::I2c	Check the supply; declare the right kInterface
NvmNotReady	STATUS nvm_rdy = 0 or nvm_err = 1 after the reset	Reset once more; if it persists, the part is faulty
PorSoftReset	Something else read INT_STATUS in between (reading clears it)	Do not poll INT_STATUS from another task during the reset

Readings

Symptom	Cause	Fix
The values never change	The chip is in standby or deep standby	Check the result of Configure() or SetPowerMode(PowerMode::Normal)
One new value, then nothing	Forced mode: one conversion, then standby	Set forced mode again per sample, or use normal mode
DataReady() never turns true	Another reader clears INT_STATUS first, or the chip is not converting	Read INT_STATUS in one place only; check the power mode
Pressure reads 0	Pressure disabled (pressure_enable = false) or ReadSample(false)	Enable pressure in OsrOdrConfig
odr_valid is false	The oversampling pair does not fit the ODR period; the chip runs with ×1 / ×1 or ×2 / ×2	Lower the oversampling or the ODR (Register interface)
Noisy pressure	Low oversampling, or air movement	Raise pressure oversampling, enable the IIR filter (SetIir()), shield the port from drafts
Offset of tens of pascals	Solder drift (±30 Pa) or self-heating	Compare against a reference once after assembly; keep the sensor away from warm parts

SPI only

Symptom	Cause	Fix
Two-byte settings come back wrong	The port sends [reg] [d0] [d1]; SPI writes do not auto-increment	Send one address byte before each data byte
Every read is shifted by one byte	The port drops a "dummy" byte the BMP581 does not send	Take data from the byte right after the address
Works until the first soft reset	A soft reset selects I2C again, and the port does not declare kInterface = Interface::Spi	Declare it: the driver then does the dummy read after the reset

Next

Hardware has the pins and bus settings; Porting the transport rules.