CC2541: peripheral losing connection if using I2C (BLE-CC254x-1.4.0)

How do you send some data (every second) using I2C (updating an OLED display)? If it would block CC2541, you might need to break the I2C operation into several part and call them piece by piece.

I already broke the communication as much as possible while still keeping the integrity of the display  picture.

I can see that there are some Connection Parameters that can be adjusted. I still use the default,which are:

#define DEFAULT_DESIRED_MIN_CONN_INTERVAL 200

#define DEFAULT_DESIRED_MAX_CONN_INTERVAL     1600

#define DEFAULT_DESIRED_SLAVE_LATENCY 1

#define DEFAULT_DESIRED_SLAVE_LATENCY         1

#define DEFAULT_DESIRED_CONN_TIMEOUT          1000

Central-Peripheral exchange information every 30 seconds so it might be possible to change parameters to be less strict ?

Any recommendations ?

Yes, you can try to increase connection interval related parameters to see if it works. By the way, how long will your I2C application code block CC2541?

using osal_GetSystemClock() (read before and after I2C ) it takes less then  1 ms

I will try experimenting with parameters. Thanks

If it takes less than 1ms, it should not cause problem. If you try not to do I2C action in your application, are you sure you don’t have disconnected issue?

If I don't do i2c (simply commented out the i2c sending functions) the connection stays on for hours

This doesn’t make sense to me. Can you attach your I2C related codes?

AppTime_withI2c.zip

Look in the timeAppClockDisplay() function where I update the LCD with i2c

Do you mean the disconnect issue disappear if you comment out "LCD_WRITE_STRING( displayBuf, HAL_LCD_LINE_3 ); " in your timeAppClockDisplay?

Let me explain:

In timeapp_clock.c starting around line 168, I have the following code:

// LCD_WRITE_STRING( displayBuf, HAL_LCD_LINE_3 );
uint32 timDiff=osal_GetSystemClock();

if(time.minutes!=lastMinute){
if(lastMinute!=100){
osal_start_timerEx( timeAppTaskId, REQUEST_TIME_FROM_SERVER_EVT, 1000); // once a minute
}
lastMinute=time.minutes;
// disp_hour(time.hour );
// disp_minute(time.minutes );
// oled_blink_colon(time.minutes); // this will be serialized after the other I2C communication
}else{
oled_blink_colon(time.minutes);
}

if I uncomment the lines

disp_hour(time.hour );
disp_minute(time.minutes );

Then I get disconnect

If I only call

oled_blink_colon(time.minutes);

which sends I2C data (about 10 bytes)  to the  display, the connection is kept alive.

I do not use any of the original LCD macros like  LCD_WRITE_STRING

Is there a yield like command that I can use to transfer control to the BLE stack while running long processes ?

There is no yield like command for application. By the way, if you comment disp_hour or disp_minute in your code, just one of them, do you see disconnection issue?

It’s good to know you solve the issue by splitting I2C operations into more smaller pieces.