Consider what my final project needs, I decided to add another PCB note here. This week is about make a distance sensor that measures, well, distance, and hopefully could distance the change on a display. The sensor I'm getting is VL53L1X. I like this sensor as it had marked down which pin is which.(After some homework on how this sensor works. I reached the conclusion I only needed four pins to make it work: VDD, GND, SDA, SCL)
I downloaded XIAO ESP32S3 Pinlist and VL53L1X Pinlist to help me with the PCB design
On the VL53L1X there are six pins: VIN, GND, SCL, SDA, GPIO, and XSHUT. It can be a bit overwhelming if you’ve never seen these before, so I looked them up and summarized what each one does:
One library needs to be installed before the real programing - VL53L1X.h
Even with simple wire connection, I run into an unexpcted problem. I wrote a program that scan the address on the sensor and the result came back shocked me. It seems the system detected 120+ devices.
How can this be? I did some research, and even though I could not be sure, but it is based on this theory that I eventually solved the issue. It seems the wire I used was too long, which means the HIGH and LOW are no longer really HIGH and LOW but somewhere floating, creating a lot of noise. So I changed to short wires, and problem gone. Now it's showing only one device! (At the address of 0x29)
#include <Wire.h>
// Change these if you’re on a board where you can re-map I2C pins (ESP32, etc.)
#ifndef SDA
#define SDA -1
#endif
#ifndef SCL
#define SCL -1
#endif
static const uint8_t VL53_ADDR = 0x29;
// ---- Low-level I2C helpers for VL53L1X register access ----
// VL53L1X uses 16-bit register addresses.
bool writeReg16(uint8_t addr, uint16_t reg, uint8_t value) {
Wire.beginTransmission(addr);
Wire.write((uint8_t)(reg >> 8));
Wire.write((uint8_t)(reg & 0xFF));
Wire.write(value);
return (Wire.endTransmission() == 0);
}
bool readReg8(uint8_t addr, uint16_t reg, uint8_t &out) {
Wire.beginTransmission(addr);
Wire.write((uint8_t)(reg >> 8));
Wire.write((uint8_t)(reg & 0xFF));
if (Wire.endTransmission(false) != 0) {
return false;
}
int n = Wire.requestFrom((int)addr, 1);
if (n != 1) return false;
out = Wire.read();
return true;
}
void i2cScan() {
Serial.println("=== I2C scan ===");
int found = 0;
for (uint8_t a = 1; a < 127; a++) {
Wire.beginTransmission(a);
uint8_t err = Wire.endTransmission();
if (err == 0) {
Serial.print(" Found device at 0x");
if (a < 16) Serial.print("0");
Serial.println(a, HEX);
found++;
}
}
Serial.print("Total I2C devices: ");
Serial.println(found);
Serial.println("=== I2C scan end ===\n");
}
void setup() {
Serial.begin(115200);
delay(800);
Serial.println("\nVL53L1X I2C + ID Test\n");
Wire.begin();
Wire.setClock(400000);
i2cScan();
Serial.println("Checking for device at 0x29...");
Wire.beginTransmission(VL53_ADDR);
uint8_t err = Wire.endTransmission();
Serial.print(" endTransmission returned: ");
Serial.println(err);
if (err != 0) {
Serial.println("\n❌ No ACK from 0x29.\n");
return;
}
Serial.println("✅ 0x29 ACKed.\n");
Serial.println("Reading Model ID (reg 0x010F)...");
uint8_t modelId = 0;
bool ok = readReg8(VL53_ADDR, 0x010F, modelId);
if (!ok) {
Serial.println("❌ Failed to read Model ID.");
return;
}
Serial.print("✅ Model ID read: 0x");
Serial.println(modelId, HEX);
}
void loop() {
delay(3000);
i2cScan();
}
Even though the sensor was placed on a stable table and measured the distance to the room ceiling, the returned values were not identical each time.
When I moved my hand close to the sensor, it did not need to physically touch the sensor for the reading to become zero. I could get a reading of 0 even when my palm was still approximately 3–4 cm away.
max(0, real_distance - threshold)
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
void setup() {
Serial.begin(115200);
// Use board default I2C pins
Wire.begin();
Wire.setClock(100000);
if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
Serial.println("SSD1306 init failed");
while (true) delay(10);
}
display.clearDisplay();
display.display();
Serial.println("OLED initialized");
}
void loop() {
static uint32_t counter = 0;
display.clearDisplay();
// Visual proof it works
display.drawRect(0, 0, 128, 64, SSD1306_WHITE);
display.fillRect(5, 5, 30, 20, SSD1306_WHITE);
display.setTextColor(SSD1306_WHITE);
display.setTextSize(2);
display.setCursor(45, 10);
display.println("TEST");
display.setTextSize(1);
display.setCursor(45, 40);
display.print("Count: ");
display.println(counter++);
display.display();
delay(200);
}