Added HX711 support

main.cpp

@@ -9,6 +9,10 @@
 #include "DHT.h"
 #endif
 
+#if MBED_CONF_APP_HX711_ENABLED
+#include "HX711.h"
+#endif
+
 using namespace events;
 
 uint8_t rx_buffer[LORAMAC_PHY_MAXPAYLOAD];
@@ -45,11 +49,22 @@ AnalogIn bat(MBED_CONF_APP_BATTERY_ADC);
 DHT dht(MBED_CONF_APP_DHT_DATA, MBED_CONF_APP_DHT_TYPE);
 #endif
 
+#if MBED_CONF_APP_HX711_ENABLED
+HX711 loadcell(MBED_CONF_APP_HX711_CLK, MBED_CONF_APP_HX711_DATA);
+#endif
+
 //DigitalOut led(LED1, 1);
 
 int main(void) {
 
     lorawan_status_t retcode;
+
+#if MBED_CONF_APP_HX711_ENABLED
+    loadcell.setScale(MBED_CONF_APP_HX711_SCALE);
+    loadcell.setOffset(MBED_CONF_APP_HX711_OFFSET);
+    loadcell.powerDown();
+#endif
+
     // Initialize LoRaWAN stack
     if(lorawan.initialize(&ev_queue) != LORAWAN_STATUS_OK) {
         printf("\r\n LoRa initialization failed! \r\n");
@@ -117,6 +132,12 @@ static void send_message() {
     }
 #endif
 
+#if MBED_CONF_APP_HX711_ENABLED
+    loadcell.powerUp();
+    cayenne.addAnalogInput(2, loadcell.getUnits(5));
+    loadcell.powerDown();
+#endif
+
     // No data to send
     if(cayenne.getSize() == 0) {
         return;

mbed_app.json.sample

@@ -27,7 +27,11 @@
         "battery-adc":         { "value": "NC" },
         "dht-enabled":         { "value": "false" },
         "dht-type":            { "value": "DHT::DHT22" },
-        "dht-data":            { "value": "NC" }
+        "dht-data":            { "value": "NC" },
+        "hx711-clk":           { "value": "NC" },
+        "hx711-data":          { "value": "NC" },
+        "hx711-scale":         { "value": "1.0f" },
+        "hx711-offset":        { "value": 0 }
     },
     "target_overrides": {
         "*": {
@@ -276,7 +280,12 @@
             "battery-adc":         "PA_2",
             "dht-enabled":         true,
             "dht-data":            "D8",
-            "dht-type":            "DHT::DHT22"
+            "dht-type":            "DHT::DHT22",
+            "hx711-enabled":       true,
+            "hx711-clk":           "D7",
+            "hx711-data":          "D6",
+            "hx711-scale":         "21000.0f",
+            "hx711-offset":        -2000
         }
     },
     "macros": ["MBEDTLS_USER_CONFIG_FILE=\"mbedtls_lora_config.h\""]

sensors/HX711.lib

@@ -0,0 +1 @@
+https://github.com/atoy40/mbed-hx711/#92640d4fcfc8f2128c3f3f54031cfafed5733bc8