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--- member-projects:m0jqq_-_bpq_for_beginners [2024/12/15 12:13] – [Monitoring a Remote Battery Voltage] m0jqq
+++ member-projects:m0jqq_-_bpq_for_beginners [2025/08/01 18:33] (current) – m0jqq
@@ Line 424: / Line 424: @@
 == Arduino code ==
+<code>
+//To measure up to 15V dc
+#define inputPin A0
+// mvpc is a measurement of actual millivolsts per count (5v ref/1064)
+const float mvpc = 4.55;
+//counts are the ouput of the adc
+float counts = 0;
+float mv = 0;
+float multi = 3;
+//multi depends on voltage divider setup (3 x 5k in series)
+float output = 0;
+void setup() {
+  // put your setup code here, to run once:
+Serial.begin (115200);
+}
+void loop() {
+  // put your main code here, to run repeatedly:
+counts = analogRead (inputPin);
+mv = counts * mvpc;
+output = (mv * multi) / 1000;
+Serial.println("GB7AAX Solar Battery = " + String(output)+" Volts");
+delay (5000);
+}
+</code>
+== Create python3 script – battMonitor.py==
+Depending on RPI OS version, you may need to install Python and/or Python libraries
+<code>
+cd ~/
+nano battMonitor.py
+#!/usr/bin python3
+import serial
+import time
+sdata = serial.Serial('/dev/serial/by-path/platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.1:1.0-port0', 115200, timeout=1.0)
+time.sleep(2)
+sdata.reset_input_buffer()
+print("Arduino Connected")
+try:
+        while True:
+                time.sleep(0.01)
+                if sdata.in_waiting >0:
+                        file = open("/tmp/beacon" ,"w")
+                        battState = sdata.readline().decode('utf-8').rstrip()
+                        file.write(f"{battState}"+"\n")
+                        file.close()
+                        print (battState)
+except KeyboardInterrupt:
+        print("Serial Comms Closed")
+        sdata.close()
+        file.close()
+</code>
+Make it executable <code> chmod +x battMonitor.py </code>
+== Create bash startup script – getBattMonitor.sh ==
+<code>
+nano getBattMonitor.sh
+#!/bin/bash
+sudo python3 /home/robin/battMonitor.py
+sleep 1
+</code>
+Make it executable <code> chmod +x getBattMonitor.sh </code>
+Now is the time to test your work. Connect a variable power supply set to less than 5 volts to the batt+ and Gnd connections of your Arduino and measure the voltage between GND & A0 It should be about one third of your variable power supply voltage.
+Start the script with <code> ~/getBattMonitor.sh </code> After a few seconds you should see something like the following...
+a <code> get /opt/oarc/bpq/beacon </code> from a second terminal should match and follow the output at 5 second intervals