+extern __data uint8_t ao_sample_data; /* Ring position of last processed sample */
+
+#if HAS_BARO
+extern __pdata pres_t ao_sample_pres; /* most recent pressure sensor reading */
+extern __pdata alt_t ao_sample_alt; /* MSL of ao_sample_pres */
+extern __pdata alt_t ao_sample_height; /* AGL of ao_sample_pres */
+extern __pdata pres_t ao_ground_pres; /* startup pressure */
+extern __pdata alt_t ao_ground_height; /* MSL of ao_ground_pres */