MAC: Fixed enhanced ack TX time

Author: Jarkko Paso

source/MAC/IEEE802_15_4/mac_mcps_sap.c

@@ -1736,7 +1736,7 @@ int8_t mcps_generic_ack_build(protocol_interface_rf_mac_setup_s *rf_ptr, const m
 
     tx_buf->len = frame_length;
     uint8_t *mhr_start = ptr;
-    buffer->tx_time = rx_time + 196; //Send 196 us later
+    buffer->tx_time = mac_mcps_sap_get_phy_timestamp(rf_ptr) + 300; //Send 300 us later
 
     ptr = mac_generic_packet_write(rf_ptr, ptr, buffer);