Softdevice slowing down TWI

[KellyJust]

Hi,

I am using the SDK 11 on nrf51822 I just merged the TWI sensor example and the BLE UART example. Both work together but the softdevice seems to be slowing down the twi read as reading the twi is taking almost double the time. Without softdevice the TWI takes the expected time. 

Any suggestions on what could be going wrong. 

[Kenneth]

Hi,

There is no easydma on the nRF51-series, so for a twi transfer each byte must be sent from the twi interrupt handler (or main context if you are using blocking twi transfer). I assume with the softdevice there may be higher priority interrupts occurring, which will effectively delay the twi transfer.

Kenneth

[KellyJust]

Thanks for the reply Kenneth. For the softdevice for now I am just advertising and then after connection doing nothing with softdevice and still there is delay in twi. There is a DFU service also running haven't tried disabling it. 

For twi I am using the blocking mode and have function calls for the twi sensor read write in the main. 

[Kenneth]

If you are using blocking mode, then any interrupt will delay the execution (e.g. app_timers, softdevice radio events etc.)

Best regards,
Kenneth