sd_ant_channel_open fails if channel assigned as EXT_PARAM_ASYNC_TX_MODE

[Mike]

Hello,

In the following code, I have tried to assign a channel to be asychronous so that I can transmit 8 byte acknowledged messages immediately following a button press. However, the call to sd_ant_channel_open() fails with error 0x4015. If I remove the EXT_PARAM_ASYNC_TX_MODE parameter from the channel assign function, then I can open the channel. What am I doing wrong?

Once the channel is open, is it the sd_ant_broadcast_message_tx() I should be using to send the 8 byte message? How do I specify how often it retries?

Thanks.

uint32_t err_code;
const uint8_t chan=0;

err_code = sd_ant_lib_config_set( ANT_LIB_CONFIG_MESG_OUT_INC_RSSI | ANT_LIB_CONFIG_MESG_OUT_INC_DEVICE_ID );
APP_ERROR_CHECK(err_code);

// MASTER channel = async Tx
err_code = sd_ant_channel_assign( chan, CHANNEL_TYPE_MASTER, 0, EXT_PARAM_ASYNC_TX_MODE );
APP_ERROR_CHECK(err_code);

// Set Channel id
uint16_t devnum = *(uint32_t *)SERIAL_NUMBER_ADDRESS;
uint8_t devtype = 1;
uint8_t txtype = 0;
err_code = sd_ant_channel_id_set( chan, devnum, devtype, txtype );
APP_ERROR_CHECK(err_code);

// Set channel radio frequency
err_code = sd_ant_channel_radio_freq_set( chan, 77 );
APP_ERROR_CHECK(err_code);

// Channel period = 1000/32768s, but do we need to set this for async Tx???
err_code = sd_ant_channel_period_set( chan, 1000 );
APP_ERROR_CHECK(err_code);

// Set Tx power = 0dBm
err_code = sd_ant_channel_radio_tx_power_set( chan, RADIO_TX_POWER_LVL_3, 0 );
APP_ERROR_CHECK(err_code);

// Open the Tx channel - this fails with error code 0x4015
err_code = sd_ant_channel_open( chan );
APP_ERROR_CHECK(err_code);

[Mike]

Having re-read "ANT Message Protocol and Usage" it says "In contrast to other channel configurations, a channel using asynchronous transmission does not need to be opened and no channel period needs to be set. Once the channel is assigned any data messages pushed to the channel will be sent over the air". So presumably that explains the error message!

I'm still unclear on how to actually send my 8 byte data, specify timeouts, and know if it's been acknowledged, though....

[Petter Myhre]

You can find the error code in ant_error.h. It is not included in all ANT examples (it should be), but you can find it in the ant_fs example. 0x4015 corresponds to NRF_ANT_ERROR_CHANNEL_IN_WRONG_STATE.

As you have figured out you get this error code because accourding to the ANT Message Protocol and Usage you shouldn't open the channel:

In contrast to other channel configurations, a channel using asynchronous transmission does not need to be opened and no channel period needs to be set.

Regarding how to send the your data, it says:

All three data types (broadcast, acknowledged and burst) are supported.

So it seems you can use either of the following:

   sd_ant_broadcast_message_tx()
   sd_ant_acknowledge_message_tx()
   sd_ant_burst_handler_request()

How do I specify how often it retries?

sd_ant_broadcast_message_tx() will send maximum 8 bytes once. It is not acknowledged, it is not retried.

sd_ant_acknowledge_message_tx() will send maximum 8 bytes once. It is acknowledged, but it is not retried. The application will be notified if it is success or failure.

sd_ant_burst_handler_request() will send x bytes. It is acknowledged, it is retried 5 times. The application will be notified if it is success or failure.