Using I2C with CMSIS

[onurdemirel]

Hello,

I am learning about CMSIS functions and started with I2C application. I have some issues that I couldn't overcome. I stucked at the beginning. 

I am using TWR-KE18F board with MCUXpresso IDE and SDK2.0. I am trying to reach the WhoAmI register of onboard accelerometer.

my piece of example code is:

EXAMPLE_I2C_MASTER.Initialize(lpi2c_master_callback);
EXAMPLE_I2C_MASTER.PowerControl(ARM_POWER_FULL);
EXAMPLE_I2C_MASTER.Control(ARM_I2C_BUS_SPEED,ARM_I2C_BUS_SPEED_STANDARD);

g_master_txBuff[0] = 0x0D;      //WhoAmI register = 0x0D
EXAMPLE_I2C_MASTER.MasterTransmit(SLAVE_ADR,g_master_txBuff,1,true);

while(!ARM_I2C_EVENT_TRANSFER_DONE)
{}
while(EXAMPLE_I2C_MASTER.GetStatus().busy)
{}

EXAMPLE_I2C_MASTER.MasterReceive(SLAVE_ADR,g_master_rxBuff,1,false);

PRINTF("0x%2x", g_master_rxBuff[0]);

and I see 0xff.

As I said I am new to this topic and any help will be appreciated. 

Thanks,

Onur

[Alice_Yang]

Hello Onur Demirel ,

I  recommend you first have a look at the demo "read_accel_value_transfer" under SDK  (SDK_2.3.0_TWR-KE18F\boards\twrke18f\driver_examples\lpi2c\read_accel_value_transfer),

there is a function about read Who AM I register of FXOS8700 on board :

also the readme.txt tell you how to run this demo on your TWR-KE18F board.

Hope it helps

Have a great day,
TIC

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[onurdemirel]

Hello Alice_Yang‌,

I am trying to use CMSIS library and I am trying to write a basic code fusing with two example code which are cmsis_lpi2c_edma_b2b_transfer_master under CMSIS examples and the one you attached. I realized I am checking the busy status in a wrong way.  

Instead of 

while(!ARM_I2C_EVENT_TRANSFER_DONE)
{}
while(EXAMPLE_I2C_MASTER.GetStatus().busy)
{}

 I need to check for 

while(!g_masterCompletionFlag)
{}

which is set upon a completion event. That is used in the CMSIS example of I2C. 

One other thing, after calling --.MasterRecieve function I need to wait for busy flag:

EXAMPLE_I2C_MASTER.GetStatus().busy

Well the main point I am struggling is the examples are too complicated for a simple I2C operation. A single write or read operation is declared in 2-3 functions concatenated. I am familiar with assembly language but it become confusing for debugging these high level example codes.

Now I am working on reading sensor data using again CMSIS libraries. I have still some problems but I am working on them  

If I feel desperate I will ask for your help again.

Thanks a lot

Onur