Overview

  • 10 uA deep sleep current
  • USB and external DC battery power inputs (3.3V - 5V)
  • battery charging from USB external DC
  • TP4056 Li-Ion battery charger
  • RT9080 Low Drop out Linear Regulator
  • supported by platformio (board=firebeetle32)

PINS

  • LED : (IO2)
  • VBAT : (A0 - 36 - SENSOR_VP) measure ratio = 0.5
  • Another caveat is the usage of pin 36 A0 which conflicts with wifi. To avoid that, in the program below, the battery is measured before the wifi is activated.
FireBeetle - DFRobot
Wiki
Schematics
User Manual
Solar Power Manager Micro

Applications

ESP32 Program Github Repo

Config 

{
    "mqtt" : {
        "host":"10.0.0.42",
        "port":1883,
        "client_id":"esp_firebeetle_1"
    },
    "base_topic":"esp/firebeetle_1",
    "deep_sleep_sec":10
}
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Main

main.cpp 
#include "Arduino.h"
#include <WiFi.h>

#include <ArduinoJson.h>
#include "freertos/FreeRTOS.h"
#include <WiFi.h>
#include <MQTT.h>
#include <esp_wifi.h>

#include "json_file.h"
#include "battery.h"
#include "wifi_secret.h"

DynamicJsonDocument config(1*1024);//5 KB
MQTTClient mqtt(1*1024);// 1KB for small messages
WiFiClient wifi;//needed to stay on global scope

void setup() {

  Serial.begin(115200);
  uint32_t vref = bat_init();
  Serial.printf("eFuse Vref:%u mV\n", vref);
  float battery_f = bat_get_voltage();
  battery_f /=1000;

  pinMode(LED_BUILTIN, OUTPUT);
  blink(100);
  WiFi.begin(ssid, password);
  load_config(config,true);
  timelog("config loaded");

  if(connect()){
    mqtt_publish_status(battery_f);    timelog("=>status");
    mqtt.loop();
  }

  Serial.println("ESP going to deep sleep");
  Serial.flush();
  blink(100);

  esp_wifi_stop();
  uint32_t deep_sleep_sec = config["deep_sleep_sec"];
  esp_deep_sleep(deep_sleep_sec*1000000);
  esp_deep_sleep_start();

}

void loop() {
  //no loop
}
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Build info... 
PACKAGES:
 - framework-arduinoespressif32 3.10004.201016 (1.0.4)
 - tool-esptoolpy 1.30000.201119 (3.0.0)
 - toolchain-xtensa32 2.50200.80 (5.2.0)
 ...
 Dependency Graph
|-- <WiFi> 1.0
|-- <ArduinoJson> 6.16.1
|-- <MQTT> 2.4.7        
|-- <FS> 1.0
|-- <SPIFFS> 1.0        
|   |-- <FS> 1.0
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Details... 
[env]
board = firebeetle32
framework = arduino
lib_deps =
    WiFi
    ArduinoJson@6.16.1
    617@2.4.7   #MQTT 256dpi/arduino-mqtt
lib_ldf_mode = deep+
[env:firebeetle32]
platform = espressif32
monitor_speed = 115200
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