Use of twi_manager with Ant

RE: Use of twi_manager with Ant

bgarrood — Thu, 04 Apr 2019 06:49:55 GMT

i have isolated it to a hardware issue. See https://devzone.nordicsemi.com/f/nordic-q-a/44485/twi-manager-interference-with-ant

RE: Use of twi_manager with Ant

Kenneth — Mon, 03 Sep 2018 06:49:48 GMT

Hi,

[quote user="bgarrood"]Is it possible that I am just asking too much of the chip? [/quote]

This should work.

Best regards,
Kenneth

RE: Use of twi_manager with Ant

bgarrood — Thu, 30 Aug 2018 16:25:35 GMT

Understood. Thank you Kenneth.

Is it possible that I am just asking too much of the chip? I am running the twi sampling loop at 100Hz, and streaming over ant at 80Hz (i.e. 80 Ant packets per second).

Otherwise I will try looking at the DK.

I have followed all guidelines on circuit layout etc..

Thank you for your help.

RE: Use of twi_manager with Ant

Kenneth — Tue, 21 Aug 2018 13:50:10 GMT

[quote user="bgarrood"]Does the TWI read take place entirely in hardware when using the twi manager schedule method? [/quote]

Yes and no. There is no dependency or resource conflicts between the radio and twi peripherals that may explain your issue, exception is the GPIO usage restrictions"-chapter in product specifications. This means that a twi transfer may occur during a radio event with no issue. That said, the twi transfer will create some noise, and if for instance you are using a module, it is especially important that you have followed the guidelines from the module manufacturer in terms of placement, grounding, and power routing, to prevent digital noise to influence analog performance. Using a nRF52-DK for comparison may be a good idea to isolate if the problem is hardware related.

It is possible for software to prevent the softdevice stack to execute as planned, either by disable interrupts, or the twi transfer is executed from an interrupt with high priority.

RE: Use of twi_manager with Ant

bgarrood — Tue, 21 Aug 2018 12:11:59 GMT

Hi Kenneth,

No, I am not (as far as I am aware) disabling interrupts.

Does the TWI read take place entirely in hardware when using the twi manager schedule method? Is there any way it can block if reading is happening at the same time as ant radio?

Range makes no difference - whether it is right next to the receiver or 1m away I get the same drop rate.

Many thanks

RE: Use of twi_manager with Ant

Kenneth — Tue, 21 Aug 2018 07:00:38 GMT

Hi Barney,

"Previously I just used twi master in blocking mode and that was causing big dropout issues due to the twi blocking the ant events."

That should not be possible, because all ANT radio events are occurring on higher interrupt priority, are you somehow disabling all interrupts here?

What kind of range are you experiencing here?

Best regards,
Kenneth

RE: Use of twi_manager with Ant

bgarrood — Mon, 20 Aug 2018 14:54:08 GMT

Hi Kenneth,

Thank you for that.

I am using my own PCB where the nrf52 is on a dynastream D52M D2M8IA board.

I use pins 2,3,4,5 for the two TWI instances, in order to steer clear of the radio. I am using the internal pull-ups on the nrf52 chip.

I believe the issue is software rather than hardware. Would yuo expect this sort of problem using twi manager with ant? Previously I just used twi master in blocking mode and that was causing big dropout issues due to the twi blocking the ant events.

Thank you
Barney

RE: Use of twi_manager with Ant

Kenneth — Mon, 20 Aug 2018 14:38:26 GMT

Hello,

Is this using your own PCB or an nRF52-DK? What gpio# have you used for the TWI instances? What pull up resistors have you used?

My first assumption is that if you are using pins close to the ANT pin, then this may affect the radio. For instance check out ("GPIO usage restrictions"-chapter in product specifications):
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/pin.html?cp=2_1_0_3_2#concept_rfc_x1z_2q

Best regards,
Kenneth