HAL API — npz_hal.h / npz_hal.c

The Hardware Abstraction Layer decouples the driver from MCU-specific I²C code. Adapt Src/npz_hal.c for your platform; see Platform Porting for examples.

Constants

#define NPZ_I2C_ADDRESS              0x7A   // 0x3D shifted left by 1
#define I2C_TRANSMISSION_TIMEOUT_MS  1300

Constant	Value	Description
NPZ_I2C_ADDRESS	0x7A	nPZero 7-bit address (0x3D) shifted left by 1, as required by most HAL APIs.
I2C_TRANSMISSION_TIMEOUT_MS	1300	Default timeout (ms) for all I²C transactions.

Return Type

All HAL functions return npz_status_e:

Value	Meaning
OK (0x00)	Operation succeeded.
ERR (0x01)	I2C transaction failed.
INVALID_PARAM (0x02)	A parameter was invalid.

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npz_hal_init

npz_status_e npz_hal_init(void);

Brief: Initializes the MCU I²C peripheral for communication with the nPZero G1S.

Description: Must be the first driver function called. The reference STM32 implementation configures I2C1 with 7-bit addressing, disables analog and digital filters, and calls HAL_I2C_Init. Replace this body when porting.

Parameters: None.

Returns: OK on success, ERR if the I²C peripheral could not be initialized.

Example:

if (npz_hal_init() != OK) {
    // I2C init failed — check clock config and pin assignments
}

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npz_hal_read

npz_status_e npz_hal_read(uint8_t slave_address, uint8_t slave_register,
                           uint8_t *pData, uint16_t size, uint32_t timeout);

Brief: Blocking I²C register read from the nPZero IC.

Description: First writes slave_register to set the read pointer, then reads size bytes into pData. The reference implementation uses HAL_I2C_Mem_Read. This function is called internally by all npz_read_* functions — do not call it directly in application code.

Parameters:

Name	Direction	Description
slave_address	in	I2C device address (use NPZ_I2C_ADDRESS = 0x7A).
slave_register	in	Target register address on the nPZero IC.
pData	out	Buffer to store the bytes read from the IC.
size	in	Number of bytes to read.
timeout	in	Timeout in milliseconds before aborting.

Returns: OK on success, ERR on I²C failure.

note

The device's 7-bit address value in the datasheet must be shifted to the left before calling this function.

note

This function is blocking.

---

npz_hal_write

npz_status_e npz_hal_write(uint8_t slave_address, uint8_t *pData,
                            uint16_t size, uint32_t timeout);

Brief: Blocking I²C write to the nPZero IC.

Description: Transmits size bytes from pData. The first byte in pData must be the target register address; subsequent bytes are data. Uses HAL_I2C_Master_Transmit in the reference implementation. Called internally by all npz_write_* functions.

Parameters:

Name	Direction	Description
slave_address	in	I2C device address (use NPZ_I2C_ADDRESS = 0x7A).
pData	in	Buffer where pData[0] is the register address and the rest is data.
size	in	Total number of bytes to transmit (register address + data).
timeout	in	Timeout in milliseconds before aborting.

Returns: OK on success, ERR on I²C failure.

note

The device's 7-bit address value in the datasheet must be shifted to the left before calling this function.

note

This function is blocking.