How to arrange Ble and Ant+ event ?

[hongpal]

Hello, Nordic

I'm developing with nrf52840, s340, sdk 16.0.0, gcc-arm-none-eabi-7-2018-q2 in my customboard.

Currently, I'm using master of Ble and Ant.

It is possible to get datas from Ble sensor once a second if I don't try to search Ant sensor.

However, if I open channel to search Ant sensor and then it is not possible to get datas from Ble sensor once a second.

I just receive 2 ~ 3 seconds delayed datas that send from ble sensor. 

Please, let me know how to solve this problem. 

[Kenneth]

Hi,

I suspect you need to disable high priority search, see here for more information:
https://www.thisisant.com/resources/an11-ant-channel-search-and-background-scanning-channel 

Add ant_search_config.c from the nRF5 SDK, then it is configured by calling ant_search_init():
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v16.0.0/group__ant__search__config.html 

For instance you need to set the following before calling ant_search_init(&search_config):

// Disable high priority search to minimize disruption to other channels while searching
search_config.high_priority_timeout = ANT_HIGH_PRIORITY_SEARCH_DISABLE;

Calling ant_search_init(&search_config) must be done before calling sd_ant_channel_open().

There should be ANT examples in the nRF5 SDK that show how you can use ant_search_init().

Best regards,
Kenneth

[hongpal]

I am doing your solution.

Howerver, I still can see delayed datas.

[Kenneth]

What are the connection parameters/interval of the BLE and ANT channels?

Best regards,
Kenneth

[hongpal]

I dont know ant interval.

How to check that? If you say ant waevform, It is default.

When is comes to ble, the min and max are 400 latency is 0

[Kenneth]

Search for sd_ant_channel_period_set().

Best regards,
Kenneth

[hongpal]

It depends on Ant+ sensor type.

So I use one of 8086, 8102, 8118, 8070,8182, 8192, 8198.

[Kenneth]

From time to time there may be collisions on air and packet loss due to interference. So that you may receive sporadic EVENT_RX_FAIL is something you should expect. In this case I notice you have a BLE interval of 500ms and an ANT channel of ~250ms. This will mean that you from time to time can get an EVENT_RX_FAIL (they drift over eachother). If you in addition open an ANT channel search you need to have the priority to low/ background search to minimize the effect on the already open ANT channel. If you still experience issues I don't think there is much you can do. You can try to configure BLE slave latency (>0) of the peripheral, this will allow to trade some lower throughput of BLE for ANT, you may also look into if you can use a different interval for BLE (e.g. ~490ms instead of 500ms).

Best regards,
Kenneth

[hongpal]

However, I can get EVENT_RX_FAIL event without connect ble. 

[Kenneth]

It is normal to get EVENT_RX_FAIL sometimes, for instance a <2-3%, how many % do you get EVENT_RX_FAIL?

I assume you are using external 32kHz crystal in your design?