nrf51422 ANT interrupts and WS2812b

RE: nrf51422 ANT interrupts and WS2812b

bradm6 — Sat, 23 Jan 2016 07:02:39 GMT

Awesome. I tried your suggestion and with a few modifications it worked. That being said I had to call my led bit banging function inside the radio notification event handler else the bit stream would get corrupted. I hypothesize that decoupling the bit banging from the radio notification event handler results in scenarios where the bit banging starts when the radio is inactive but changes to active a short while later. We are using ANT with a very small period which likely causes issues on the bit banging (which occurs at a different frequency).

All in all it appears to be stable now. Thank you for all your help Kenneth!

RE: nrf51422 ANT interrupts and WS2812b

Kenneth — Fri, 22 Jan 2016 10:01:09 GMT

It was originally made for BLE, but I can't see any problem to use it for ANT also. The underlying softdevice call is at least identical, only the SDK library use the ble_ prefix.

RE: nrf51422 ANT interrupts and WS2812b

bradm6 — Thu, 21 Jan 2016 18:30:10 GMT

Oh nice thats what I was looking for. When I saw this before I was lead to believe this only works for bluetooth. This does work with ANT as well correct?

RE: nrf51422 ANT interrupts and WS2812b

Kenneth — Thu, 21 Jan 2016 17:43:28 GMT

Updated the answer with an example. Hope it helps.

RE: nrf51422 ANT interrupts and WS2812b

bradm6 — Wed, 20 Jan 2016 00:37:26 GMT

Thank you for the response. I did see chapter 7 describing the radio notification but I am not sure how it is used. The soft device specification does not seem to provide information on how it would be used (functions etc) and a look at the SDK documentation only provides function prototypes.. Do you think you could provide an example?

RE: nrf51422 ANT interrupts and WS2812b

Kenneth — Tue, 19 Jan 2016 10:27:31 GMT

You can find in the S210 softdevice specification the interrupt latency the softdevice will introduce during an ANT protocol event, see chapter 11: www.nordicsemi.com/.../51629523

Note: To find which S210 softdevice specification document that apply to your S210 release, you should check the nRF51 Series Compatibility Matrix first.

If you are using a master channel, you can find in the ANT power profiles in chapter 12 that a transmit is always followed by a receive period. This receive period is used for possible bi-directional data from the slave, the event might extend further if for instance the slave is sending a burst-transmission or ask for an acknowledge of data. The receive period is also used for adaptive transmission, to allow many ANT devices to communicate concurrently without interference from one another.

The only way to be sure that the ANT event is complete is to use radio notification as described in chapter 7. You can then start bit-banging after nACTIVE signal with no interrupts until next ANT event.

You might include the ble_radio_notification module in the SDK to enable radio notifications.

#include "ble_radio_notification.h"

ble_radio_notification_init(APP_IRQ_PRIORITY_LOW,
NRF_RADIO_NOTIFICATION_DISTANCE_800US,
ble_radio_notification_evt_handler);

Callback:

static bool m_radio_active;
void ble_radio_notification_evt_handler(bool radio_active)
{
    m_radio_active = radio_active;
}

Then you simply need to wait for !m_radio_active.