app_state: convert observe to work with json

Convert obsevation of the "desired" LightDB State path to directly monitor
the "reset_cumulative" value.

This is necessary because the LightDB Observe API call for the Golioth
Firmware SDK only allows JSON-type observation. A PR has been opened to
allow CBOR to be selected. This commit can be reverted when that option is
available.

Signed-off-by: Mike Szczys <[email protected]>

prj.conf

@@ -33,6 +33,10 @@ CONFIG_NET_LOG=y
 CONFIG_NET_SHELL=y
 CONFIG_REBOOT=y
 
+# Adjust coap setting for a long (16-char) LightDB State sub-path
+CONFIG_COAP_EXTENDED_OPTIONS_LEN=y
+CONFIG_COAP_EXTENDED_OPTIONS_LEN_VALUE=16
+
 # Flash memory (etc.) for firmware upgrade
 CONFIG_FLASH=y
 CONFIG_FLASH_MAP=y

src/app_sensors.c

@@ -143,6 +143,26 @@ static int log_sensor_values(adc_node_t *sensor, bool get_new_reading)
 			sensor_value_to_double(&cur),
 			sensor_value_to_double(&pow)
 			);
+
+		IF_ENABLED(CONFIG_LIB_OSTENTUS, (
+			char ostentus_buf[32];
+			uint8_t slide_num;
+
+			snprintk(ostentus_buf, sizeof(ostentus_buf), "%.02f V",
+				 sensor_value_to_double(&vol));
+			slide_num = (sensor->ch_num == 0) ? CH0_VOLTAGE : CH1_VOLTAGE;
+			slide_set(slide_num, ostentus_buf, strlen(ostentus_buf));
+
+			snprintk(ostentus_buf, sizeof(ostentus_buf), "%.02f mA",
+				 sensor_value_to_double(&cur) * 1000);
+			slide_num = (sensor->ch_num == 0) ? CH0_CURRENT : CH1_CURRENT;
+			slide_set(slide_num, ostentus_buf, strlen(ostentus_buf));
+
+			snprintk(ostentus_buf, sizeof(ostentus_buf), "%.02f W",
+				 sensor_value_to_double(&pow));
+			slide_num = (sensor->ch_num == 0) ? CH0_POWER : CH1_POWER;
+			slide_set(slide_num, ostentus_buf, strlen(ostentus_buf));
+		));
 	} else {
 		return -ENODATA;
 	}
@@ -288,11 +308,19 @@ int reset_cumulative_totals(void)
 		adc_ch0.total_unreported = 0;
 		adc_ch1.total_unreported = 0;
 		k_sem_give(&adc_data_sem);
-		return 0;
 	} else {
 		LOG_ERR("Could not reset cumulative values; blocked by semaphore.");
 		return -EACCES;
 	}
+
+	/* Send new values to Golioth */
+	int err = app_state_report_ontime(&adc_ch0, &adc_ch1);
+
+	if (err) {
+		LOG_ERR("Unable to send ontime to server: %d", err);
+	}
+
+	return err;
 }
 
 /* This will be called by the main() loop */
@@ -365,6 +393,16 @@ static void get_cumulative_handler(struct golioth_client *client,
 		return;
 	}
 
+	if ((payload_size == 1) && (payload[0] == 0xf6)) {
+		/* 0xf6 is Null in CBOR */
+		if (k_sem_take(&adc_data_sem, K_MSEC(300)) == 0) {
+			adc_ch0.loaded_from_cloud = true;
+			adc_ch1.loaded_from_cloud = true;
+			k_sem_give(&adc_data_sem);
+		}
+		return;
+	}
+
 	uint64_t decoded_ch0 = 0;
 	uint64_t decoded_ch1 = 0;
 	bool found_ch0 = 0;

src/app_state.c

@@ -89,12 +89,16 @@ int app_state_observe(struct golioth_client *state_client)
 
 	app_state_update_actual();
 
+	char observe_path[64];
+
+	snprintk(observe_path, sizeof(observe_path), "%s/%s", APP_STATE_DESIRED_ENDP,
+		 DESIRED_RESET_KEY);
 	int err = golioth_lightdb_observe_async(client,
-						APP_STATE_DESIRED_ENDP,
+						observe_path,
 						app_state_desired_handler,
 						NULL);
 	if (err) {
-	   LOG_WRN("failed to observe lightdb path: %d", err);
+		LOG_WRN("failed to observe lightdb path: %d", err);
 	}
 	return err;
 }
@@ -168,6 +172,8 @@ int app_state_report_ontime(adc_node_t *ch0, adc_node_t *ch1)
 			}
 		}
 		k_sem_give(&adc_data_sem);
+	} else {
+		return -EACCES;
 	}
 
 	return 0;
@@ -189,41 +195,16 @@ static void app_state_desired_handler(struct golioth_client *client,
 
 	LOG_HEXDUMP_DBG(payload, payload_size, APP_STATE_DESIRED_ENDP);
 
-	if ((payload_size == 1) && (payload[0] == 0xf6)) {
-		/* This is `null` in CBOR */
-		LOG_ERR("Endpoint is null, resetting desired to defaults");
-		app_state_reset_desired();
+	if (strncmp(payload, "false", strlen("false")) == 0) {
 		return;
-	}
-
-	struct zcbor_string key;
-	bool reset_cumulative;
-	bool ok;
-
-	ZCBOR_STATE_D(decoding_state, 1, payload, payload_size, 1);
-	ok = zcbor_map_start_decode(decoding_state) &&
-	     zcbor_tstr_decode(decoding_state, &key) &&
-	     zcbor_bool_decode(decoding_state, &reset_cumulative) &&
-	     zcbor_map_end_decode(decoding_state);
-
-	if (!ok) {
-		LOG_ERR("ZCBOR Decoding Error");
-		LOG_HEXDUMP_ERR(payload, payload_size, "cbor_payload");
+	} else if (strncmp(payload, "true", strlen("true")) == 0) {
+		LOG_INF("Request to reset cumulative values received. Processing now.");
+		reset_cumulative_totals();
 		app_state_reset_desired();
-		return;
-	} else if (strncmp(key.value, DESIRED_RESET_KEY, strlen(DESIRED_RESET_KEY)) != 0){
-		LOG_ERR("Unexpected key received: %.*s", key.len, key.value);
+	} else {
+		LOG_ERR("Desired State Decoding Error");
+		LOG_HEXDUMP_ERR(payload, payload_size, "desired_state");
 		app_state_reset_desired();
 		return;
-	} else {
-		LOG_DBG("Decoded: %.*s == %s",
-			key.len,
-			key.value,
-			reset_cumulative ? "true" : "false");
-		if (reset_cumulative) {
-			LOG_INF("Request to reset cumulative values received. Processing now.");
-			reset_cumulative_totals();
-			app_state_reset_desired();
-		}
 	}
 }