I2C Communication and Sensors¶
I2C interface¶
The I2C bus uses two pins:
- SCL — clock
- SDA — data
Connect SCL, SDA, power (3.3 V or 5 V as required by the sensor), and GND.
Access the bus via p.I2C.
I2C function calls¶
Scan the I2C bus and return addresses that responded (0–127).
Example: HMC5883L (address 0x1E = 30)
from eyes17 import eyes
p = eyes.open()
print(p.I2C.scan())
# e.g. [30]
Write bytes to an I2C slave.
| parameter | description |
|---|---|
| address | slave address 0–127 |
| bytestream | list of bytes |
HMC5883L: set measurement range
# CONFB register = 0x01; gain in bits 5–7
p.I2C.writeBulk(30, [0x01, 1 << 5])
Read bytes starting at register regaddr.
| parameter | description |
|---|---|
| address | slave address |
| regaddr | starting register |
| numbytes | how many bytes to read |
| return | list of bytes, or False on timeout |
HMC5883L: read X, Y, Z raw data
from numpy import int16
vals = p.I2C.readBulk(30, 0x03, 6)
Bx = int16(vals[0] << 8 | vals[1])
By = int16(vals[2] << 8 | vals[3])
Bz = int16(vals[4] << 8 | vals[5])
print(Bx, By, Bz)
Set I2C bus frequency in Hz (default is typically ~100–400 kHz depending on firmware).
p.I2C.config(100000) # 100 kHz
Auto-detect and read sensors¶
p.guess_sensor() scans the bus and, for known addresses, returns a list of initialized sensor objects from eyes17.SENSORS.
Sensors with first-class connect() support in guess_sensor():
| Address | Sensor | Docs |
|---|---|---|
0x48 |
ADS1115 | page |
0x23 |
BH1750 | page |
0x77 |
BMP180 | — |
0x78 / 118 |
BMP280 / BME280 | page |
0x29 |
VL53L0X | page |
0x68 |
MPU6050 | page |
0x1E |
HMC5883L | page |
0x0D |
QMC5883L | see HMC5883L page |
0x5A |
MLX90614 | page |
0x39 |
TSL2561 | page |
0x40 |
SHT21 | — |
0x57 |
MAX30100 (logger) | page |
SPI devices use p.SPI, not I2C.
p.guess_sensor()
from eyes17 import eyes
p = eyes.open()
sens = p.guess_sensor()
# DETECTED : [30]
# ____DOCS____ : HMC5883L ...
print(sens[0].getRaw())
# or sens[0].getVals() depending on the driver
Manually initialize a known sensor
from eyes17 import eyes
from eyes17.SENSORS import HMC5883L, TSL2561, MPU6050, BMP280
p = eyes.open()
mag = HMC5883L.connect(p.I2C, address=0x1E)
print(mag.getRaw())
light = TSL2561.connect(p.I2C)
print(light.getRaw()) # [total, IR, ...]
Example sensors¶
Detailed pages:
from eyes17 import eyes
from eyes17.SENSORS import MPU6050, TSL2561
p = eyes.open()
print(MPU6050.connect(p.I2C).getRaw())
print(TSL2561.connect(p.I2C).getRaw())
Non-I2C: ultrasonic SR04¶
Distance via SQ2/IN2 is covered under Digital I/O:
print(p.sr04_distance(), 'cm')
Graphical sensor logger¶
The ExpEYES / SEELab desktop app includes I2C Modules → General Purpose I2C Sensors: auto-detect, live gauges, logging, and curve fitting.
I2C Modules → General Purpose I2C Sensors
Gauges
Logging and analysis
Android app / Blockly
