Better makefile, plotting, saving the data, and cleanup

.gitignore

@@ -1,3 +1,4 @@
 build/
 .cache/
 sdkconfig*
+data/

Makefile

@@ -1,6 +1,17 @@
+help:
+	# plot - Plot the latest measurement
+	# monitor - Build and monitor onto esp if connected to /dev/ttyUSB0
+	# env - Start the esp environment on nix
+	# server - Start the go server
+	
 monitor:
 	idf.py -p /dev/ttyUSB0 flash monitor
+
 env:
 	nix --experimental-features 'nix-command flakes' develop github:mirrexagon/nixpkgs-esp-dev#esp32-idf
+
+plot:
+	nix-shell --pure --run "python plot.py"
+
 server:
 	go run main.go

main.go

@@ -1,12 +1,39 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"log"
 	"net/http"
+	"os"
+	"path/filepath"
+	"time"
 )
 
+var dataFile *os.File
+
+type VoltageData struct {
+	Voltage float64 `json:"voltage"`
+}
+
+func initDataFile() {
+	// Ensure the data/ directory exists
+	if err := os.MkdirAll("data", os.ModePerm); err != nil {
+		log.Fatalf("Failed to create data directory: %v", err)
+	}
+
+	// Generate a filename with timestamp
+	filename := filepath.Join("data", fmt.Sprintf("voltages_%s.txt", time.Now().Format("20060102_150405")))
+	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		log.Fatalf("Failed to open data file: %v", err)
+	}
+
+	dataFile = file
+	log.Printf("Logging voltage data to %s\n", filename)
+}
+
 func handler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		http.Error(w, "POST only", http.StatusMethodNotAllowed)
@@ -20,13 +47,31 @@ func handler(w http.ResponseWriter, r *http.Request) {
 	}
 	defer r.Body.Close()
 
-	fmt.Println("Received:", string(body))
+	// Parse JSON
+	var v VoltageData
+	if err := json.Unmarshal(body, &v); err != nil {
+		http.Error(w, "invalid JSON", http.StatusBadRequest)
+		return
+	}
+
+	// Print voltage to console
+	fmt.Println("Received voltage:", v.Voltage)
+
+	// Append voltage number to file
+	if dataFile != nil {
+		if _, err := dataFile.WriteString(fmt.Sprintf("%f\n", v.Voltage)); err != nil {
+			log.Printf("Failed to write to file: %v", err)
+		}
+	}
 
 	w.WriteHeader(http.StatusOK)
 	w.Write([]byte("ok"))
 }
 
 func main() {
+	initDataFile()
+	defer dataFile.Close()
+
 	http.HandleFunc("/data", handler)
 
 	addr := ":8080"

main/station_example_main.c

@@ -1,6 +1,6 @@
 /*
  Voltage measurement device over wifi from WiFi station Example
-  */
+*/
 
 #include <string.h>
 
@@ -33,42 +33,13 @@
 // TODO: Determine this
 #define CALIBRATION_FACTOR 1650.0f
 
-/* The examples use WiFi configuration that you can set via project configuration menu
-
-   If you'd rather not, just change the below entries to strings with
-   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
-*/
-#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+// Settings for wifi
+#define EXAMPLE_ESP_WIFI_SSID      "Jaguar"
 #define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
-#define EXAMPLE_ESP_MAXIMUM_RETRY  CONFIG_ESP_MAXIMUM_RETRY
 
-#if CONFIG_ESP_STATION_EXAMPLE_WPA3_SAE_PWE_HUNT_AND_PECK
-#define ESP_WIFI_SAE_MODE WPA3_SAE_PWE_HUNT_AND_PECK
-#define EXAMPLE_H2E_IDENTIFIER ""
-#elif CONFIG_ESP_STATION_EXAMPLE_WPA3_SAE_PWE_HASH_TO_ELEMENT
-#define ESP_WIFI_SAE_MODE WPA3_SAE_PWE_HASH_TO_ELEMENT
-#define EXAMPLE_H2E_IDENTIFIER CONFIG_ESP_WIFI_PW_ID
-#elif CONFIG_ESP_STATION_EXAMPLE_WPA3_SAE_PWE_BOTH
 #define ESP_WIFI_SAE_MODE WPA3_SAE_PWE_BOTH
 #define EXAMPLE_H2E_IDENTIFIER CONFIG_ESP_WIFI_PW_ID
-#endif
-#if CONFIG_ESP_WIFI_AUTH_OPEN
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_OPEN
-#elif CONFIG_ESP_WIFI_AUTH_WEP
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WEP
-#elif CONFIG_ESP_WIFI_AUTH_WPA_PSK
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WPA_PSK
-#elif CONFIG_ESP_WIFI_AUTH_WPA2_PSK
 #define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WPA2_PSK
-#elif CONFIG_ESP_WIFI_AUTH_WPA_WPA2_PSK
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WPA_WPA2_PSK
-#elif CONFIG_ESP_WIFI_AUTH_WPA3_PSK
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WPA3_PSK
-#elif CONFIG_ESP_WIFI_AUTH_WPA2_WPA3_PSK
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WPA2_WPA3_PSK
-#elif CONFIG_ESP_WIFI_AUTH_WAPI_PSK
-#define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WAPI_PSK
-#endif
 
 // Tag for logging
 static const char *TAG = "VoltageSensor";
@@ -93,7 +64,7 @@ static void event_handler(void* arg, esp_event_base_t event_base,
     if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
         esp_wifi_connect();
     } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
-        if (s_retry_num < EXAMPLE_ESP_MAXIMUM_RETRY) {
+        if (s_retry_num < 3) {
             esp_wifi_connect();
             s_retry_num++;
             ESP_LOGI(TAG, "retry to connect to the AP");

plot.py

@@ -0,0 +1,31 @@
+import os
+import matplotlib.pyplot as plt
+import numpy as np
+
+DATA_DIR = "data"
+SAMPLE_INTERVAL_MS = 300  # time between measurements in milliseconds
+
+# Find the latest data file
+files = [f for f in os.listdir(DATA_DIR) if f.startswith("voltages_") and f.endswith(".txt")]
+if not files:
+    raise FileNotFoundError("No voltage data files found in 'data/'")
+
+latest_file = max(files, key=lambda f: os.path.getmtime(os.path.join(DATA_DIR, f)))
+filepath = os.path.join(DATA_DIR, latest_file)
+print(f"Plotting data from {filepath}")
+
+# Load voltage values
+voltages = np.loadtxt(filepath)
+
+# Create time axis (in seconds)
+times = np.arange(len(voltages)) * (SAMPLE_INTERVAL_MS / 1000.0)
+
+# Plot
+plt.figure(figsize=(10, 5))
+plt.plot(times, voltages, marker='o', linestyle='-')
+plt.xlabel("Time (s)")
+plt.ylabel("Voltage (V)")
+plt.title(f"Voltage Measurements ({latest_file})")
+plt.grid(True)
+plt.tight_layout()
+plt.show()

pytest_wifi_station.py

@@ -1,43 +0,0 @@
-# SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
-# SPDX-License-Identifier: Unlicense OR CC0-1.0
-import os
-from typing import Callable
-from typing import Tuple
-
-import pytest
-from pytest_embedded import Dut
-from pytest_embedded_idf.utils import idf_parametrize
-# diff of esp32s2/esp32s3 ~45K, others ~50K
-
-DIFF_THRESHOLD = {
-    'esp32s2': 40 * 1000,
-    'esp32s3': 40 * 1000,
-    'default': 45 * 1000,
-}
-
-
-@pytest.mark.wifi_two_dut
-@pytest.mark.parametrize('count, config, skip_autoflash', [(2, 'default|enable_softap', 'y')], indirect=True)
-@idf_parametrize(
-    'target',
-    ['esp32', 'esp32c2', 'esp32c3', 'esp32s2', 'esp32s3', 'esp32c5', 'esp32c6', 'esp32c61'],
-    indirect=['target'],
-)
-def test_wifi_sdkconfig_disable_softap_save_binary_size(
-    dut: Tuple[Dut, Dut],
-    log_performance: Callable[[str, object], None],
-) -> None:
-    # dut logs are not needed
-    dut[0].serial.close()
-    dut[1].serial.close()
-
-    app_without_softap = dut[0].app
-    app_with_softap = dut[1].app
-    assert app_without_softap.sdkconfig['ESP_WIFI_SOFTAP_SUPPORT'] is False
-    assert app_with_softap.sdkconfig['ESP_WIFI_SOFTAP_SUPPORT'] is True
-
-    diff = os.path.getsize(app_with_softap.bin_file) - os.path.getsize(app_without_softap.bin_file)
-    log_performance('wifi_disable_softap_save_bin_size', f'{diff} bytes')
-
-    diff_threshold = DIFF_THRESHOLD.get(dut[0].target) or DIFF_THRESHOLD['default']
-    assert diff > diff_threshold

shell.nix

@@ -0,0 +1,10 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    (pkgs.python313.withPackages (p: with p; [
+      matplotlib
+      numpy
+    ]))
+  ];
+}