ESP32 (ESPRESSIF)

Firmware ESP
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1

無線機能を使用したスケッチ実行時のエラー

Brownout detector was triggered

ets Jun  8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:1216
ho 0 tail 12 room 4
load:0x40078000,len:10944
load:0x40080400,len:6388
entry 0x400806b4

WifiやBluetoothの無線機能使用時(BLE:Bluetooth Low Enegyは未確認)、USBからの給電容量を超えた電流が必要になるため、電圧のドロップダウンが発生。この電圧降下が原因でESP32のハードリセット・再起動が繰り返される。

USB-UARTの電源（USB）とは別に、ESP32の電源(DC12-DC3.3Vコンバータ)を用意することで回避（グランド共通）。

電源のラインノイズ対策：パイパスコンデンサの挿入、電源ラインとグランドラインのリード線をツイストすること。

esp32_dev_board
esp32_dev_board6061×4261 641 KB

esp32+switch
esp32+switch750×640 59.8 KB

LM2596 Step-Down Switching Regulator

CP2102 USB 2.0 To UART

2

BOOTスイッチを押下した状態でRESETスイッチを押すことで、アップロードモードに切り替わります。アップロード完了後、RESETスイッチを押すことで読み込んだソフトで動作します。

アップロード条件は以下の通りです。

esp32-wifi-scan
esp32-wifi-scan840×912 78.1 KB

3

ESP32 Pinout Reference

GPIO Input Output Notes
0 pulled up OK outputs PWM signal at boot
1 TX pin OK debug output at boot
2 OK OK connected to on-board LED
3 OK RX pin HIGH at boot
4 OK OK
5 OK OK outputs PWM signal at boot
6 x x connected to the integrated SPI flash
7 x x connected to the integrated SPI flash
8 x x connected to the integrated SPI flash
9 x x connected to the integrated SPI flash
10 x x connected to the integrated SPI flash
11 x x connected to the integrated SPI flash
12 OK OK boot fail if pulled high
13 OK OK
14 OK OK outputs PWM signal at boot
15 OK OK outputs PWM signal at boot
16 OK OK
17 OK OK
18 OK OK
19 OK OK
21 OK OK
22 OK OK
23 OK OK
25 OK OK
26 OK OK
27 OK OK
32 OK OK
33 OK OK
34 OK input only
35 OK input only
36 OK input only
39 OK input only
4

チップID定義（MACアドレスから）

uint32_t chipId = 0;

void setup() {
  Serial.begin(115200);
}

void loop() {
  for(int i=0; i<17; i=i+8) {
    chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
  }

  Serial.printf("ESP32 Chip model = %s Rev %d\n", ESP.getChipModel(), ESP.getChipRevision());
  Serial.printf("This chip has %d cores\n", ESP.getChipCores());
  Serial.print("Chip ID: "); Serial.println(chipId);
  
  delay(3000);

}
5

LittleFS_esp32

https://www.arduino.cc/reference/en/libraries/littlefs_esp32/

#define USE_LittleFS

#include <FS.h>
#ifdef USE_LittleFS
  #define SPIFFS LITTLEFS
  #include <LITTLEFS.h> 
#else
  #include <SPIFFS.h>
#endif

Differences with SPIFFS

  • LittleFS has folders, you need to iterate files in folders unless you set #define CONFIG_LITTLEFS_SPIFFS_COMPAT 1
  • At root a “/folder” = “folder”
  • Requires a label for mount point, NULL will not work. Recommended is to use default LITTLEFS.begin()
  • maxOpenFiles parameter is unused, kept for compatibility
  • LITTLEFS.mkdir(path) and LITTLEFS.rmdir(path) are available
  • file.seek() behaves like on FFat see more details
  • file.write() and file.print() when partition space is ending may return different than really written bytes (on other FS is also inconsistent).
  • Speed comparison based on LittleFS_test.ino sketch (for a file 1048576 bytes):
Filesystem Read time [ms] Write time [ms]
FAT 276 14493
LITTLEFS 446* 16387
SPIFFS 767 65622

*The read speed improved by changing #define CONFIG_LITTLEFS_CACHE_SIZE from 128 to 512

6

ESP WiFiManager

Double Reset Detector

7

ESP32モデル一覧（2026年時点）

ESP32 Comparison Chart - All Versions, Types & Models (2026 Guide)

モデルを選択しエクセルフォーマットでエクスポート可。

name title ESP32-S2 ESP32-C3 ESP32-S3 ESP32-D0WDR2-V3 ESP32-C6 ESP32-H2FH4
Overview Series ESP32-S2 ESP32-C3 ESP32-S3 ESP32 ESP32-C6 ESP32-H2
Overview CPU Xtensa® single-core 32-bit LX7 32-bit RISC-V single-core processor Xtensa® dual-core 32-bit LX7 Xtensa® dual-core 32-bit LX6 32-bit RISC-V single-core processor 32-bit RISC-V single-core processor
Overview Core 1 1 2 2 1 1
Overview Freq. (MHz) 240 160 240 240 160 96
Overview Package (mm) QFN56 (7*7) QFN32 (5*5) QFN56 (7*7) QFN48(5*5) QFN40(5*5) QFN32(4*4)
Overview Dimensions (mm) 7*7 5*5 7*7 5*5 5*5 4*4
Overview Voltage (V) 3.0 ~ 3.6 3.0 ~ 3.6 3.0 ~ 3.6 2.3 ~ 3.6 3.0 ~ 3.6 3.3 ~ 3.6
Overview Temp. (℃) -40 ℃ ~ 105 ℃ -40 ℃ ~ 105 ℃ -40 ℃ ~ 105 ℃ -40 ℃ ~ 85 ℃ -40 ℃ ~ 105 ℃ -40 ℃ ~ 105 ℃
Overview Status Mass Production Mass Production Mass Production EOL Mass Production Replaced
Overview ECO standard version standard version standard version ECO V3
Overview Chip Revision v1.x v0.x v0.x v4.1.3+, v4.2.3+, v4.3.3+, v4.4.1+, v5.0 and later v0.x v0.x
Wireless Wi-Fi IEEE 802.11b/g/n; 2.4 GHz; HT20/40; up to 150 Mbps IEEE 802.11b/g/n; 2.4 GHz; HT20/40; up to 150 Mbps IEEE 802.11b/g/n; 2.4 GHz; HT20/40; up to 150 Mbps IEEE 802.11b/g/n; 2.4 GHz; HT20/40; up to 150 Mbps IEEE 802.11b/g/n; 2.4 GHz; HT20/40; up to 150 Mbps N/A
Wireless Wi-Fi 6 N/A N/A N/A N/A IEEE 802.11b/g/n/ax; 2.4 GHz; HT20; up to 150 Mbps N/A
Wireless Thread N/A N/A N/A N/A Available Available
Wireless Bluetooth N/A Bluetooth LE v5.0 Bluetooth LE v5.0 BR/EDR + Bluetooth LE v4.2 Bluetooth LE v5.3 Bluetooth LE v5.3
Memory SRAM (KB) 320 400 512 520 512 320
Memory ROM (KB) 128 384 384 448 320 128
Memory RTC SRAM (KB) 16 8 16 16 16 4
Memory Flash (MB) 0, Quad 0, Quad 0, Quad 0, Quad 0, Quad 4, Quad
Memory PSRAM (MB) 0, Quad 0, Quad 0, Quad 2, Quad 0, Quad 0, Quad
Peripherals ADC 2*13-bit ADC, 20 channels 2*12-bit ADC, 6 channels 2*12-bit ADC, 20 channels 2*12-bit ADC, 18 channels 1*12-bit ADC, 7 channels 1*12-bit ADC, 5 channels
Peripherals DAC 2*8-bit DAC 0 0 2*8-bit DAC 0 0
Peripherals Touch 14 14 10
Peripherals Temp Sensor 1 1 1 1 1
Peripherals GPIO 43 22 45 33 30 19
Peripherals Strapping GPIO 0, 45, 46 2, 8, 9 0, 3, 45, 46 0, 2, 5, 12, 15
Peripherals GPIO for flash/PSRAM 27, 28, 29, 30, 31, 32 / 11, 12, 13, 14, 15, 16, 17 / 27, 28, 29, 30, 31, 32 / 6, 7, 8, 9, 10, 11 / 16 / /
Peripherals UART 2 2 3 3 3 2
Peripherals SPI 4 3 4 4 1 3
Peripherals SDIO HOST 2 1
Peripherals SDIO SLAVE 1 1
Peripherals I2C 2 1 2 2 2 2
Peripherals I2S 1 1 2 2 1 1
Peripherals RMT 1*4 channels 1*4 channels 1*8 channels 1*8 channels 4
Peripherals LED PWM 1*8 channels 1*6 channels 1*8 channels 2*8 channels 1*6 channels
Peripherals MCPWM 0 0 2 2
Peripherals USB OTG 1 1
Peripherals Hall 1
Peripherals Ethernet 1
Peripherals TWAI 1 1 1 1 2 1
Peripherals JTAG YES YES YES YES YES
Peripherals Camera 1*DVP 8/16-bit N/A 1*DVP 8/16-bit 1*DVP 8/16-bit N/A N/A
Peripherals TOF YES N/A N/A N/A N/A N/A
Certification BT Certification BT SIG BT SIG BT SIG BQB BQB
Certification Wi-Fi Certification Wi-Fi Alliance/WPA 3 Thread Thread
Certification Zigbee Certification Zigbee Zigbee
Certification Thread Certification Thread 1.4 Thread 1.4
8

ESP32-C6