OPT3001

Overview

The OPT3001 is a precision ambient light sensor from Texas Instruments that measures illuminance in lux and communicates via the I²C bus. This driver provides a simple API for initialization, reading lux values, and retrieving device information. It is designed for use with the TM4C1294XL LaunchPad and the BOOSTXL-EDUMKII BoosterPack.

I²C0 PB2/PB3 Continuous conversion mode

---

Features

• Operates on I²C0 using PB2 (SCL) and PB3 (SDA).
• Provides lux readings in floating-point format.
• Supports continuous measurement mode with automatic range adjustment.
• Includes helper functions to read Manufacturer ID and Device ID.
• Configurable default integration time (800 ms).

---

Basic Usage

#include "OPT3001.h"

int main(void)
{
    uint32_t sysclk = SysCtlClockFreqSet(
        SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
        SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480, 120000000);

    // Initialize the OPT3001 sensor
    OPT3001_Init();

    // Read a lux value
    float lux = OPT3001_ReadLux();
}

---

API Summary

Function	Description
void OPT3001_Init(void)	Initializes the I²C peripheral and configures the sensor.
void OPT3001_WriteRegister(uint8_t reg, uint16_t value)	Writes a 16-bit value to a register.
uint16_t OPT3001_ReadRegister(uint8_t reg)	Reads a 16-bit register value.
uint16_t OPT3001_ReadManufacturerID(void)	Returns the manufacturer ID (should be 0x5449).
uint16_t OPT3001_ReadDeviceID(void)	Returns the device ID (should be 0x3001).
float OPT3001_ReadLux(void)	Returns the measured lux value.

---

I²C Configuration

The OPT3001 communicates using I²C0, mapped as follows:

Signal	Pin	MCU Port	Function
SCL	PB2	GPIOB	I2C0SCL
SDA	PB3	GPIOB	I2C0SDA

---

Example: Reading and Printing Lux via UART

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom_map.h"
#include "OPT3001.h"

uint32_t g_ui32SysClock;

void UARTSend(const char *pui8Buffer)
{
    while(*pui8Buffer)
    {
        MAP_UARTCharPut(UART0_BASE, *pui8Buffer++);
    }
}

static void UART0_Init(void)
{
    MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
    MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

    MAP_GPIOPinConfigure(GPIO_PA0_U0RX);
    MAP_GPIOPinConfigure(GPIO_PA1_U0TX);
    MAP_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);

    MAP_UARTConfigSetExpClk(UART0_BASE, g_ui32SysClock, 115200,
                            (UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
                             UART_CONFIG_PAR_NONE));
}

int main(void)
{
    g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
                                             SYSCTL_OSC_MAIN |
                                             SYSCTL_USE_PLL |
                                             SYSCTL_CFG_VCO_240), 120000000);

    UART0_Init();
    OPT3001_Init();

    char buffer[64];
    while (1)
    {
        float lux = OPT3001_ReadLux();
        snprintf(buffer, sizeof(buffer), "Lux = %.2f lx\r\n", lux);
        UARTSend(buffer);
        SysCtlDelay(g_ui32SysClock / 3);  // ~1s
    }
}

---

Integration Notes

• Ensure 3.3V logic levels; do not connect to 5V I²C devices.
• Pull-up resistors on SCL and SDA (typically 4.7kΩ) are required for stable communication.
• The sensor automatically handles gain and range adjustment; no manual scaling is needed.
• Use SysCtlDelay() or timer-based delays between reads to avoid over-sampling.

License and Credits

Developed for ECE3849 — Real-Time Embedded Systems. Based on TI’s TivaWare and OPT3001 datasheet.

Author: Edwin R. Version 1.0