C2541: Long I2C Misses Bytes

Bill Finger

Other Parts Discussed in Thread: CC2541

I am sending long packets (832 bytes) to the CC2541 over I2C. Sometimes some of bytes, up to 10! are lost. Other times the entire packet is transmitted successfully. See the graphic below. In this case, the byte with the value 0x29 was not received. As can be observed, there was a long delay on the bus between this byte and the next. I believe this delay was caused by the CC2541 'clock stretching' the bus.

Any ideas? I have already disabled clock halting during the RF periods.

Regards,

Bill

over 11 years ago

0 J Lindh over 11 years ago

TI__Guru 57865 points

Hi Bill,

You could try to disable the clock divide by;

  HCI_EXT_ClkDivOnHaltCmd( HCI_EXT_DISABLE_CLK_DIVIDE_ON_HALT );

Best Regards

Joakim

0 Bill Finger over 11 years ago

Genius 3735 points

There ended up being two problems. One, unlike most platforms I have worked with, interrupts are enabled inside interrupt handlers. So, I had to disable interrupts inside the I2C ISR, or other interrupts would interfere.

Secondly, if you reset SI and there is still an interrupt condition available, that interrupt may be missed. To solve this issue I now loop until STAT reads 0xF8 before leaving the ISR.

0 Peter Borenstein over 11 years ago in reply to Bill Finger

Mastermind 8695 points

What will you do if you get a link layer interrupt while looping in the I2C ISR?

0 Bill Finger over 11 years ago in reply to Peter Borenstein

Genius 3735 points

The interrupt will be serviced when the I2C interrupt completes. To date I have not had any problems with the connection.

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C2541: Long I2C Misses Bytes