From c3d58f88db34aed0bfa09b39ad479fd3a7967067 Mon Sep 17 00:00:00 2001
From: alanbjohnston <alan.b.johnston@gmail.com>
Date: Tue, 17 Sep 2019 13:36:10 -0400
Subject: [PATCH] replaced NaN with 0; and tested value for -1 and set fd -1 if
 not present on bus

---
 afsk/main.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/afsk/main.c b/afsk/main.c
index f7e08c68..0c245e56 100644
--- a/afsk/main.c
+++ b/afsk/main.c
@@ -156,9 +156,9 @@ struct SensorData {
  */
 struct SensorData read_sensor_data(struct SensorConfig sensor) {
     struct SensorData data = {
-        .current = NAN,
-        .voltage = NAN,
-        .power = NAN    };
+        .current = 0,
+        .voltage = 0,
+        .power = 0    };
 
     if (sensor.fd < 0) {
         return data;
@@ -168,6 +168,11 @@ struct SensorData read_sensor_data(struct SensorConfig sensor) {
     wiringPiI2CWriteReg16(sensor.fd, INA219_REG_CONFIG, sensor.config);	
     wiringPiI2CWriteReg16(sensor.fd, INA219_REG_CALIBRATION, sensor.calValue);
     int value  = wiringPiI2CReadReg16(sensor.fd, INA219_REG_CURRENT);
+    if (value == -1)
+    {
+	sensor.fd = -1;
+	return data;
+    }
     data.current  = (float) twosToInt(value, 16) / (float) sensor.currentDivider;
 	
     wiringPiI2CWrite(sensor.fd, INA219_REG_BUSVOLTAGE);