hpaluch / i2c-cjmcu-75

Using I2C CJMCU-75 board with digital temperature sensor LM75A

Using I2C board CJMCU-75 with LM75A

Here is sample project how to use CJMCU-75 board with I2C LM75A Digital Temperature Sensor.

Project status:

• Now can read temperature using: LC CH341A USB Adapter - project in VS2010. See project's readme for more details.

Setup

Here is reverse engineered schematic (drawn in Express SCH) of CJMCU-75 with LM75A address set to 0:

NOTE:

I was surprised that the resistor labeled 300 is actually 200K Ohm (I would expect 30 * 10^0 = 30 Ohm which would be strange, but...) This is even value which I get on SMD resistor code calculator

You need to set I2C Device address before using CJMCU-75.

I set device address to 0 soldering these pins (see above picture):

1. A0 and GND together.
2. A1 and GND together.
3. A2 and GND together.

After soldering all three pins - A0, A1 and A2 to one of GND or VCC the board is ready for use.