ESP32Overview

ESP32-C3

Espressif's first RISC-V part, and still the value benchmark for the whole family. A dollar for a 160 MHz core with Wi-Fi, BLE 5 and hardware crypto — and six years of accumulated documentation.

The dependable dollar chip.

Production Announced 2020, production 2021 Availability committed from 2020-01-01

$1.00 chip, from
CPU
Single-core RISC-V
Clock
40–160 MHz
Low-power core
None
On-chip SRAM
400 KB
PSRAM
External only, up to 8 MB
Flash
Up to 4 MB in-package, 16 MB external
Wi-Fi
Wi-Fi 4 (2.4 GHz)
Bluetooth
Bluetooth 5 (LE)
802.15.4
No
GPIO
22
USB
USB Serial/JTAG only
Deep sleep
~5 µA
Package
QFN 5×5
Reference dev board
ESP32-C3-DevKitM-1 ($8)

Stands out for

Espressif's first RISC-V part; the most mature cheap option, with hardware ECC

Watch out for

Single core, no low-power core, no USB OTG, no Wi-Fi 6

Typical designs

Switches and sockets, lighting, simple sensors, ESP8266 replacements

The C3 was announced in 2020 as Espressif’s first RISC-V chip and its answer to the question “what replaces the ESP8266?”. Six years later it is neither the fastest, the most efficient nor the most featured part in the family — and it is still the one to recommend to most people building most things.

The argument is boring and correct: at $1.00 for the chip and $8 for the development board, with 400 KB of SRAM, a 160 MHz core, Wi-Fi, Bluetooth LE 5 and hardware ECC, the C3 has no gap between what it claims and what it delivers. Every framework supports it properly. Every tutorial works. The errata are known and worked around. Nothing about it will surprise you at integration time.

For a sensor that reads a value and posts it somewhere, a relay controller, a switch, a light, or a first ESP32 project, this is the right chip and has been for years.

Where the C3 sits against the C6

This is the comparison that matters, since the C6 costs only 85 cents more:

ESP32-C3ESP32-C6
Wi-FiWi-Fi 4 (802.11n)Wi-Fi 6 (802.11ax)
BluetoothBLE 5BLE 5.3 + Mesh
Thread / ZigbeeNoYes (802.15.4)
Low-power coreNoYes, 20 MHz RISC-V
SRAM400 KB512 KB
GPIO2230
Security certificationPSA Level 1PSA Level 2
Chip price from$1.00$1.85

On specifications the C6 wins comprehensively. Choose the C3 anyway when the extra features are genuinely unused — a mains-powered device on a quiet network does not benefit from Target Wake Time — or when the ecosystem maturity gap matters more than the feature gap, or when 85 cents times your volume is a number that gets discussed.

Architecture notes

A single RISC-V core at up to 160 MHz, and single-core has the usual consequence: the Wi-Fi and Bluetooth stacks run on the same core as your application. A tight loop or a long blocking call will cause dropped packets. Write event-driven code, keep interrupt handlers short, and do not fight it.

There is no ULP or LP coprocessor. A small RTC memory region survives deep sleep for a handful of variables, but nothing executes while the main core is down. Deep-sleep current is around 5 µA, which is genuinely good — better than the C6’s 7 µA — but the sleep pattern available to you is limited to wake-on-timer or wake-on-GPIO. You cannot, for example, have a coprocessor average thirty ADC readings over a minute and only wake the main core if the trend crosses a threshold. On the C6 or C5, you can.

On the security side the C3 has hardware AES-128/256, SHA-1/224/256, RSA-3072, ECC and HMAC, plus secure boot v2 and flash encryption, and carries a PSA Level 1 certification. Its ECC support is real hardware, not bignum emulation.

Peripherals

  • 22 GPIOs (16 on some package variants)
  • 3 SPI controllers, 1 I2S, 1 I2C (master and slave), 2 UART
  • USB Serial/JTAG — flash and debug over one USB cable with no external adapter, but no USB device classes
  • TWAI (CAN 2.0), which the C2 lacks
  • 4 RMT channels (2 TX, 2 RX) — addressable LEDs, IR, one-wire sensors all work
  • 6-channel 12-bit ADC and an internal temperature sensor
  • No touch sensing, no DAC, no Ethernet MAC, no SD/MMC

Modules and boards

ESP32-C3-MINI-1 from $1.80 (the -N4-A variant) is the cheapest module in the entire Espressif catalogue; ESP32-C3-WROOM-02 from $1.90 is the larger-footprint alternative. Both have U external-antenna variants. Espressif also sells this die as ESP8685, with ESP8685-WROOM modules at $2.25.

ESP32-C3-DevKitM-1 is $8. Two specialist kits are worth knowing about: ESP32-C3-DevKit-RUST-2 ($18), built specifically for the Rust esp-rs toolchain with an onboard IMU and sensors, and ESP32-C3-AWS-ExpressLink-DevKit-2 ($25). ESP32-C3-Lyra targets audio and LED-strip applications, and ESP32-C3-LCDkit pairs a 1.28-inch round display with a rotary encoder.

Third-party: Seeed’s XIAO ESP32-C3 is the standout — a genuinely tiny board with a battery connector, widely used in wearables and small sensors.

Choose it when

  • You want the best ratio of capability to hassle at the bottom of the market
  • The device is mains powered on a network that is not congested
  • You are learning, prototyping, or building a one-off
  • You need RMT for LEDs, IR or one-wire sensors on a budget
  • You want RISC-V with the most mature tooling in the family

Choose something else when

  • You need Thread, Zigbee, Matter-over-Thread or Wi-Fi 6 → ESP32-C6
  • You need a coprocessor active during deep sleep → ESP32-C6 or ESP32-C5
  • There is a display or camera involved → ESP32-S3
  • You need USB device classes → ESP32-S2 or ESP32-S3
  • Volume pricing is everything → ESP32-C2