To program the ESP-01, you must set the state of specific pins before powering on or resetting the device: GPIO 0 must be tied to GND. Normal Run Mode: GPIO 0 must be floating or tied to VCC.
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The ESP-01 is a small but powerful Wi-Fi module based on the ESP8266 SoC. It is widely used for IoT projects because it is cheap and simple to use. This guide covers everything you need to know from the datasheet, including pinouts, power needs, and setup. Technical Specifications
| Pin | Name | Function | |-----|------|-----------| | 1 | GND | Ground | | 2 | GPIO2 | I/O (high on boot) | | 3 | GPIO0 | Boot mode (LOW = flash, HIGH = run) | | 4 | RXD | UART RX (3.3V logic) | | 5 | TXD | UART TX | | 6 | CH_PD | Chip enable (HIGH to operate) | | 7 | RST | Reset (active LOW) | | 8 | VCC | 3.3V input | esp 01 datasheet
The original ESP-01 datasheet is sparse. Here’s the real-world takeaway:
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The ESP-01 is limited (only 2 usable GPIOs, 3.3V logic, current spikes), but it’s perfect for simple IoT switches, sensors, or controlling a relay. Always use a level shifter or voltage divider if connecting to 5V logic. To program the ESP-01, you must set the
General-purpose I/O. Pull LOW to enter programming mode; HIGH for normal run. RST: External reset. Active LOW. RX / GPIO 3: UART Data Receive. Also used as a general I/O. VCC: Power supply (3.3V ONLY). Power Requirements and Warnings
The is the smallest and most cost-effective member of the ESP8266 family. It is a self-contained SoC (System on Chip) with integrated TCP/IP protocol stacks, allowing any microcontroller to connect to a Wi-Fi network. It is widely used in IoT (Internet of Things) applications due to its low footprint and low power consumption.
To operate the ESP-01 reliably, the following connections are recommended: The ESP-01 is a small but powerful Wi-Fi
The ESP-01 is a compact, 3.3V Wi-Fi module based on the ESP8266 chipset, featuring a 32-bit RISC processor, 802.11 b/g/n, and two general-purpose I/O pins. It supports AT commands for serial-to-Wi-Fi bridging and is commonly programmed via the Arduino IDE for IoT applications. Learn more about the ESP-01 module at MakerHero .
The ESP-01 module put Wi-Fi into the hands of hobbyists. Before the ESP8266 NodeMCU or ESP32, there was this tiny 8-pin board. If you’re working with one today, here’s what you need from its datasheet.
Add Wi-Fi capability to non-connected devices.
✅ 3.3V only (no 5V) ✅ GPIO: 0, 2, RX, TX (only 0 & 2 are safely usable for outputs) ✅ Flash mode: GPIO0 → GND on boot ✅ Current: 200-300 mA peak – use a good 3.3V regulator