ESP-12E (ESP8266): specs and pinout
A bare Ai-Thinker ESP-12E Wi-Fi module (ESP8266 with 4 MB flash and PCB antenna) with 22 pads at 2 mm pitch.
Specs
| Spec | Value | Source |
|---|---|---|
| Operating voltage | 3.0 V to 3.6 V (3.3 V typical) | source Table 1 (p.6); Table 8 Recommended Operating Conditions (p.14) |
| Average operating current | 80 mA | source Table 1 Parameters (p.6) |
| Operating temperature | -40 C to 125 C | source Table 1 (p.6); Table 8 (p.14) |
| Wi-Fi | 802.11 b/g/n, 2.4 GHz (2400-2483.5 MHz); station / softAP / SoftAP+station | source Table 1 Parameters (p.6) |
| Flash | 4 MB external SPI flash | source Section 3 (p.9); 4.2.2 (p.11) |
| Size | 16 mm x 24 mm x 3 mm, pin pitch 2 mm | source Table 5 Dimension (p.11) |
| I/O levels | VIL max 0.25 VDD; VIH min 0.75 VDD, max VDD + 0.3 V; VOL max 0.1 VDD; VOH min 0.8 VDD | source Table 9 Digital Terminal Characteristics (p.14) |
| ADC input range | 0 to 1 V | source Table 3 Pin Descriptions, pin 2 (p.7) |
| Deep-sleep current | 10 uA typical | source Table 11 Power Consumption (p.16) |
Power
| Value | Source | |
|---|---|---|
| Supply | 3.0 V to 3.6 V (3.3 V typ) | source Table 11 Power Consumption (p.16) |
| Current | TX 802.11b 170 mA (+17 dBm), 11g 140 mA, 11n 120 mA; RX 50 to 56 mA; modem-sleep 15 mA; light-sleep 0.9 mA; deep-sleep 10 uA | source Table 11 Power Consumption (p.16) |
Pinout
Pin names and functions are copied from the Ai-Thinker ESP-12E Specification v1.0 (module, 22 pads). Any adapter board used with it is a separate product.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | RST | Reset the module | source Table 3 Pin Descriptions (p.7-8) | |
| 2 | ADC | A/D conversion result. Input voltage range 0-1v, scope: 0-1024 | source Table 3 Pin Descriptions (p.7-8) | |
| 3 | EN | Chip enable pin. Active high | source Table 3 Pin Descriptions (p.7-8) | |
| 4 | IO16 | GPIO16; can be used to wake up the chipset from deep sleep mode | source Table 3 Pin Descriptions (p.7-8) | |
| 5 | IO14 | GPIO14; HSPI_CLK | source Table 3 Pin Descriptions (p.7-8) | |
| 6 | IO12 | GPIO12; HSPI_MISO | source Table 3 Pin Descriptions (p.7-8) | |
| 7 | IO13 | GPIO13; HSPI_MOSI; UART0_CTS | source Table 3 Pin Descriptions (p.7-8) | |
| 8 | VCC | 3.3 V | 3.3V power supply (VDD) | source Table 3 Pin Descriptions (p.7-8) |
| 9 | CS0 | Chip selection | source Table 3 Pin Descriptions (p.7-8) | |
| 10 | MISO | Slave output Main input | source Table 3 Pin Descriptions (p.7-8) | |
| 11 | IO9 | GPIO9 | source Table 3 Pin Descriptions (p.7-8) | |
| 12 | IO10 | GPIO10 (written GBIO10 in the sheet) | source Table 3 Pin Descriptions (p.7-8) | |
| 13 | MOSI | Main output slave input | source Table 3 Pin Descriptions (p.7-8) | |
| 14 | SCLK | Clock | source Table 3 Pin Descriptions (p.7-8) | |
| 15 | GND | GND | source Table 3 Pin Descriptions (p.7-8) | |
| 16 | IO15 | GPIO15; MTDO; HSPICS; UART0_RTS | source Table 3 Pin Descriptions (p.7-8) | |
| 17 | IO2 | GPIO2; UART1_TXD | source Table 3 Pin Descriptions (p.7-8) | |
| 18 | IO0 | GPIO0 | source Table 3 Pin Descriptions (p.7-8) | |
| 19 | IO4 | GPIO4 | source Table 3 Pin Descriptions (p.7-8) | |
| 20 | IO5 | GPIO5 | source Table 3 Pin Descriptions (p.7-8) | |
| 21 | RXD | UART0_RXD; GPIO3 | source Table 3 Pin Descriptions (p.7-8) | |
| 22 | TXD | UART0_TXD; GPIO1 | source Table 3 Pin Descriptions (p.7-8) |
Build with it
Project ideas for the ESP-12E (ESP8266). Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Deep-sleep temperature node: The adapter holds the module and the USB serial board flashes it; the sheet says GPIO16 (pin 4) can wake the chip from deep sleep. A learning project.
- Wi-Fi weather display: I2C OLED and the DHT22 data pin on free GPIOs; avoid GPIO0, 2 and 15 for them because of their boot roles.
- Wi-Fi DC current and voltage logger: The INA219 chip runs from 3 to 5.5 V and measures bus voltage from 0 to 26 V over I2C (TI datasheet), so it can use IO4 and IO5 (pins 19 and 20) at 3.3 V logic; the CJMCU module itself is not documented, so check its markings. Learning project: keep the measured circuit low-voltage.
Common mistakes
- Supply is 3.0 to 3.6 V only; 5 V on VCC exceeds the sheet range (source: link, Table 8, p.14).
- Boot mode is set by GPIO15, GPIO0 and GPIO2: UART download needs GPIO15 low, GPIO0 low, GPIO2 high; flash boot needs GPIO15 low, GPIO0 high, GPIO2 high (source: link, Table 4 Pin Mode, p.8).
- The ADC pin accepts 0 to 1 V only (source: link, Table 3, p.7).
Not covered by the official source
- Sheet has ESP-12E and ESP-12F style headings; the sheet copyright is 2015 and its version is 1.0.