topic Re: Problem with setting I2C address using KDS in Kinetis Microcontrollers

Problem with setting I2C address using KDS

johns_chuang — Fri, 13 Jan 2023 06:36:04 GMT

Dear

I am trying to communicate with a temperature IC using the I2C of TRK-KEA8, the slave address of the temperature IC is 0x4C,

but the code generated by Components-DGP_LDD can only send 0x98,

I have tried the following three methods but they were all ineffective:

1. Changing the I2C_LLD setting in Components Inspector to 0x4C or 76, did not work.

2. Adding the SelectSlaveDevice instruction in the program, did not work.

3. Directly modifying the values inside CI2C1_Init() initialization, did not work.

Are there any other methods or have I misunderstood or missed anything?

Thank you for your time.

Re: Problem with setting I2C address using KDS

bobpaddock — Fri, 13 Jan 2023 12:57:20 GMT

I2C puts the read/write bit in the lowest bit, so addresses get shifted to the left. 0x4C * 2 = 0x98.

Some data sheets give the shifted value others give the unshifted value for the device's address. You may really need to enter 0x26 = (0x4C / 2). Always a point of confusion with I2C.

Re: Problem with setting I2C address using KDS

johns_chuang — Mon, 16 Jan 2023 01:27:30 GMT

Hi Bobpaddock

Thank you for the detailed explanation, it is very helpful to me. Thank you.