refactor (firmware): simplify web server client for reading batt voltage

hutscape · Apr 11, 2024 · 97cd3e2 · 97cd3e2
1 parent b89bc51
commit 97cd3e2
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Showing 3 changed files with 30 additions and 18 deletions.
diff --git a/_code/measure-battery-level.md b/_code/measure-battery-level.md
@@ -11,6 +11,10 @@ references:
     url: https://github.com/espressif/arduino-esp32/blob/master/variants/esp32c3/pins_arduino.h
   - name: Create an Access Point
     url: https://raw.githubusercontent.com/espressif/arduino-esp32/990e3d5b431b63b4adc364b045a79afdad645a3f/libraries/WiFi/examples/WiFiAccessPoint/WiFiAccessPoint.ino
+  - name: How to check the battery voltage
+    url: https://wiki.seeedstudio.com/check_battery_voltage/
+  - name: Power Management
+    url: https://learn.adafruit.com/adafruit-feather-m4-express-atsamd51/power-management#measuring-battery-3010518
 difficulty: medium
 features:
   - esp32c3
@@ -29,5 +33,5 @@ images:
 1. Remove the USB-C cable used for firmware upload
 1. Turn on the power switch
 1. Connect to access point `batt` with password `12345678`
-1. Browser to `http://192.168.4.1/` on the browser
+1. Browser to `http://192.168.4.1` on the browser
 1. View `hello world`
diff --git a/_code/measure-battery-level/Makefile b/_code/measure-battery-level/Makefile
@@ -9,7 +9,7 @@ BUILD = build
 default: lint compile upload clean
 
 lint:
-	cpplint --extensions=ino --filter=-legal/copyright,-runtime/int *.ino
+	cpplint --extensions=ino --filter=-legal/copyright,-runtime/int,-readability/todo *.ino
 
 compile: clean lint
 	arduino-cli compile --fqbn $(BOARD) --output-dir $(BUILD) ./

diff --git a/_code/measure-battery-level/measure-battery-level.ino b/_code/measure-battery-level/measure-battery-level.ino
@@ -4,6 +4,9 @@
 #include <WiFiClient.h>
 #include <WiFiAP.h>
 
+#define BATTERY_ENABLE_PIN 6
+#define BATTERY_MEASURE_PIN 5
+
 const char *ssid = "batt";
 const char *password = "12345678";
 WiFiServer server(80);
@@ -34,25 +37,30 @@ void loop() {
     String currentLine = "";
     while (client.connected()) {
       if (client.available()) {
-        char c = client.read();
-        Serial.write(c);
-        if (c == '\n') {
-          if (currentLine.length() == 0) {
-            client.println("HTTP/1.1 200 OK");
-            client.println("Content-type:text/html");
-            client.println();
-            client.print("hello world");
-            client.println();
-            break;
-          } else {
-            currentLine = "";
-          }
-        } else if (c != '\r') {
-          currentLine += c;
-        }
+        client.println("HTTP/1.1 200 OK");
+        client.println("Content-type:text/html");
+        client.println();
+        client.print("hello world");
+        client.println();
+        break;
       }
     }
     client.stop();
     Serial.println("Client Disconnected.");
   }
 }
+
+float measureBatteryVoltage() {
+  pinMode(BATTERY_ENABLE_PIN, OUTPUT);
+  digitalWrite(BATTERY_ENABLE_PIN, HIGH);
+
+  delay(100);
+
+  int rawValue = analogRead(BATTERY_MEASURE_PIN);
+  // TODO: Fix schematic to use 10k instead of 100k
+  float voltage = rawValue * (3.3 / 4095);
+
+  digitalWrite(BATTERY_ENABLE_PIN, LOW);
+
+  return voltage;
+}