samples: lorawan: class_a: add datarate callback

Add an example callback implementation that prints out the new maximum
payload given the updated datarate.

Signed-off-by: Jordan Yates <[email protected]>

Author: Jordan Yates

samples/lorawan/class_a/src/main.c

@@ -32,6 +32,14 @@ LOG_MODULE_REGISTER(lorawan_class_a);
 
 char data[] = {'h', 'e', 'l', 'l', 'o', 'w', 'o', 'r', 'l', 'd'};
 
+static void lorwan_datarate_changed(enum lorawan_datarate dr)
+{
+	uint8_t unused, max_size;
+
+	lorawan_get_payload_sizes(&unused, &max_size);
+	LOG_INF("New Datarate: DR_%d, Max Payload %d", dr, max_size);
+}
+
 void main(void)
 {
 	const struct device *lora_dev;
@@ -53,6 +61,8 @@ void main(void)
 		return;
 	}
 
+	lorawan_register_dr_changed_callback(lorwan_datarate_changed);
+
 	join_cfg.mode = LORAWAN_ACT_OTAA;
 	join_cfg.dev_eui = dev_eui;
 	join_cfg.otaa.join_eui = join_eui;