I2C Detection Fail

[coder_72]

Hello everyone,

I have a problem with the OM40001 sample "lpcxpresso804_lpc_i2c_interrupt_b2b_transfer_slave". I have removed the bridges for the LM75 and agreed on a slave on SCL PIO0_14 and SDA PIO0_7. I can't find the device on my agreed address with an I2C detect with an I2C master. I have connected SCL with SCL and SDA with SDA.
Does anyone have a solution? Thanks a lot.

[xiangjun_rong]

Hi,

I have downloaded the data sheet of LM75, which is a temperature sensor with I2C interface, but the LPC75 can only be a I2C slave in stead of master, if you use the I2C module of LPC804 with SCL PIO0_14 and SDA PIO0_7, the I2C module of LPC804 is master.

For the device address of LM75, it has A2/A1/A0 pins, this is address format.

xiangjun_rong_0-1672022324982.png

Assume that the A2/A1/A0 pin logic is 000 via pull up/down resistors, the I2C device address of LM75 is 0x48. Assume that the A2/A1/A0 pin logic is 011, the I2C device address of LM75 is 0x4B.

Because the I2C of LPC804 is master, so you have to use the

xiangjun_rong_2-1672022619602.png

Hope it can help you

BR

XiangJun Rong