ESP32-C61

The proposition

The C61 is best understood as a cost-reduced C6. Same 160 MHz single RISC-V core, same Wi-Fi 6 on 2.4 GHz, same Bluetooth LE 5, same 30 GPIOs — for $1.46 instead of $1.85, with modules at $2.14 instead of $2.50.

What pays for the difference:

The trades are coherent for a specific kind of product: a mains-powered Wi-Fi device — an appliance controller, a Wi-Fi adapter, a POS terminal, a smart-home actuator — that benefits from Wi-Fi 6’s congestion behaviour but will never join a Thread network and does not need a coprocessor running during sleep.

The two omissions that catch people out

No RMT. As on the C2, this means no hardware pulse timing: no clean WS2812/NeoPixel driving, no IR transmit or receive, no DS18B20 one-wire sensors without bit-banging. This surprises people who assume all modern ESP32 parts have it. If your product has an addressable LED strip or an IR remote, the C61 is the wrong chip.

One ADC channel. Not six or seven — one. If you need to read more than a single analogue sensor, you are adding an external ADC over I2C or SPI, which erases the cost saving.

What it does have

Interestingly, the C61 is better than the C6 in one respect: it supports in-package PSRAM (2 or 8 MB), where the C6 requires external PSRAM. For a Wi-Fi device that needs buffer space — a small web UI, an OTA staging area, an audio buffer — that can be the deciding factor.

On security it is stronger than its price suggests. It has hardware AES, SHA, RSA and ECC, plus an ECDSA-based digital signature peripheral that holds the private key in eFuses where software cannot read it, and APM plus PMP for memory isolation. That ECDSA-DS peripheral is genuinely absent from the C6, which only has the RSA-flavoured version.

Other peripherals: 2 SPI, 1 I2S, 1 I2C, 3 UART, USB Serial/JTAG, SDIO 2.0 slave (so it can act as a host co-processor), TWAI, LED PWM and a temperature sensor.

Modules and boards

ESP32-C61-MINI-1 at $2.14 and ESP32-C61-WROOM-1 at $2.60, both with U external-antenna variants. Bare chips: ESP32-C61 at $1.46 and ESP32-C61HF4 (4 MB flash) at $1.51.

Espressif has not released a dedicated low-cost DevKit at the same visibility as the C6’s, so evaluation generally starts from a module on a carrier or a third-party board. Espressif’s longevity commitment runs from 2025.

Choose it when

• You want Wi-Fi 6 at the lowest possible cost
• The device is mains powered, or wakes often enough that ~10 µA sleep is irrelevant
• You need in-package PSRAM with a Wi-Fi 6 radio
• You need an eFuse-backed ECDSA signature peripheral
• Thread and Zigbee are definitively not in the roadmap

Choose something else when

• You need Thread, Zigbee or Matter-over-Thread → ESP32-C6
• You have addressable LEDs, IR or one-wire sensors (no RMT) → ESP32-C3 or ESP32-C6
• You need more than one ADC channel → ESP32-C6
• Battery life is critical → ESP32-C6 or ESP32-H21
• You need PSA Level 2 certification → ESP32-C6
• Wi-Fi 4 would do → ESP32-C3 is cheaper still and more capable elsewhere