No Interrupts on nRF51822 w/S110

RE: No Interrupts on nRF51822 w/S110

Yokoyama, Atsushi — Tue, 03 Mar 2015 02:46:23 GMT

Hello everyone.

I'm very new to nRF51 and S110, but I was facing to the same problem for a couple of days. Do we have some progress in this topic? Does any new version of S110 have workaround to this?

FYI, the reason I needed a time critical control is a UART peer device requires odd-parity even though nRF51 supports only even-parity so I needed bit-banging.

Best Regards,

Atsushi

RE: No Interrupts on nRF51822 w/S110

Antonio — Thu, 20 Mar 2014 15:33:48 GMT

Thank you Alex, thats a great workaround. And thank you Torbjørn for the information.

I am testing Alex tip and it seems like a good workaround while you get the new SoftDevice out. If there is a way to test the beta of that version I am in :).

Thanks again for the workaround and the later solution.

Antonio.

RE: No Interrupts on nRF51822 w/S110

ovrebekk — Thu, 20 Mar 2014 09:36:28 GMT

It should be ready in about a month or so. If you need something sooner you can try the good tip from Alex, and use the radio notification feature.

Typically the SPI master can live with interrupts, as the master is in control of the data transfer. Will your slave time out if the delay between bytes is too large?

We have many different plans for the future, unfortunately I can't reveal specifics yet...

RE: No Interrupts on nRF51822 w/S110

Alex Shepherd — Wed, 19 Mar 2014 22:15:58 GMT

Hi Antonio,

Have a look here: github.com/.../nrf51-neopixel and look for "ble_radio_notification_init" as we had the same type of issue driving the WS2812B LEDs with some timing critical software.

The solution in this case was to configure the BLE stack to notify the main loop every time it becomes not-active and then you've got several ms to quickly do your own processing before you need to hand processing time back to the BLE stack.

HTH

Alex Shepherd

RE: No Interrupts on nRF51822 w/S110

Antonio — Wed, 19 Mar 2014 18:55:41 GMT

Awesome, Torbjørn!!! :-)

Do you have a time frame for this new version? Do you have an alpha or beta that I could test?

btw, I have to do this because the Master SPI does not have DMA. Any plans in the future?

Thanks, Antonio.

RE: No Interrupts on nRF51822 w/S110

ovrebekk — Wed, 19 Mar 2014 15:44:18 GMT

Hi Antonio

Yes, you can close down the S110 stack and do some processing before enabling it again, but any running connection with the master will be disconnected. In other words you will have to reconnect after you wake up again.

How long it takes to enable the stack is a bit application specific (depending on how many services you configure and so forth), but we did some testing on the heart rate example showing the start up delay to be around 5ms.

The good news is that we are working on a new SoftDevice API that would allow you to request time slots in which you are guaranteed not to be interrupted by the stack. With this feature you could simply ask for a time slot from the stack, and the stack would find a free time slot in between any scheduled BLE events. Then you could run 2ms of blocking code without having to worry about issues, and without having to disable the stack and break existing connections.

Regards Torbjørn

RE: No Interrupts on nRF51822 w/S110

Antonio — Wed, 19 Mar 2014 14:16:25 GMT

Hi Torbjørn,

Thank you for your prompt response.

Maybe I would be twisting things by trying this out but, if it is a slave, could I quickly close the S110, or any other state that would be safe, and init it again after those 2ms? If this is posible, how long would this stop/start procedure take?

Thanks again,

Antonio.

RE: No Interrupts on nRF51822 w/S110

ovrebekk — Wed, 19 Mar 2014 13:59:15 GMT

Hi Antonio

Unfortunately the SoftDevice was designed under the assumption that it would always have the highest interrupt priority, which means that critical SoftDevice events should never be interrupted.

I can tell you with 100% certainty that if the SoftDevice was interrupted for as much as 2ms it would break sooner or later..

Regards Torbjørn