The Picoclick-C3 is the big brother of the C3T. It is a tiny WiFi and BLE IoT button for several applications. Originally designed for smart home things, the Picoclick can also be used as an actuator for IFTTT automations or as an MQTT device. It is based on the single core ESP32-C3 RISC-V processor and therefore comes with tons of useful features. Next to the usage of it as on IoT-button the C3 is able to be used as a tiny development board because it has an extension port where external hardware can be connected to.

Compared to the Picoclick-C3T the C3 comes with the most advanced features:

• It embeds a battery protection on the board itself which lets you use those tiny battery packs used by bluetooth headsets and co. Furthermore the battery protection of the Picoclick-C3 consumes only 2µA of current, whereas a standard circuit in ready to use battery packs needs 3,5µA.
• Due to the optimized battery voltage monitoring circuit, there is no current consumption of it in idle state anymore. It is based on a one-shot voltage divider, which will only be activate for a small period.
• The boot jumper can be used if an unrepairable software bug destroys the flashing process. It brings the Picoclick in a boot mode after restart.
• It can now be used as an USB powered device. A battery is not necessary.
• The FPC extension port brings this device on a complete new level!

Specifications

• ESP32-C3 RISC-V 160MHz processor
• WiFi 2.4GHz & Bluetooth LE
• Ultra small size: 18x22mm
• Extension port for external hardware
• Ultra low power: 2µA in idle state (used completely by the battery protection)
• Single cell LiPo battery charger with status LED
• 2x APA102 2020 RGB LED
• USB Type-C for battery charging and flashing (and powering if you want)
• Optimized battery monitoring with one-shot voltage divider

What makes it special?

For sure the FPC extension port is the most interesting feature of the Picoclick-C3. The port leads out the battery voltage, the switched 3.3V output of the device, two pulled-up GPIOs and the button line, which can be used to externally activate the Picoclick. With two pulled-up GPIOs on this port, the device is able to communicate with other hardware over I2C. Furthermore the button line can be used to let this external hardware activate the Picoclick device by firing an interrupt or trigger an output. For example:

• An externally connected accelerometer can be hook up via I2C and its interrupt pin can activate the Picoclick on any motion, on a single tap or on a double tap on the device.
• The output of an externally connected PIR sensor can be used to activate the Picoclick.
• A digital light sensor can be connected via I2C which activates the Picoclick on a specific light condition.

FPC Breakout board

With the extension port on the Picoclick-C3 it is easy to connect to other hardware. In order to use the Picoclick to develop new projects, the FPC cable can be broke out with this FPC breakout board and an FPC cable, which can be added to the order if you want. Further documentation of the breakout board can be found here.

Extension boards

Apart from the breakout board there are ready-to-use boards for the extension port available:

• Motion sensor extension with the LIS3DH accelerometer.
• Light sensor extension with the LTR303 light sensor.
• GPIO expander extension with the MCP23008 GPIO expander.
• OLED extension with the SSD1306 0.49" or 0.69" OLED display.
• Encoder extension with the EC11 encoder.

Except the OLED extensions, all these boards can be used to activate the Picoclick by firing an interrupt or, for the encoder extension, pressing the middle button.

Software development

The Picoclick makes use of the native USB/JTAG-console of the ESP32-C3 and therefore doesn't need a USB2Serial adapter like a CP2102N or CH340. Flashing and working with the serial console/monitor can be done as usual. Furthermore the C3 comes with an optimized latching circuit which enables easy software development with the Arduino framework, because the timing optimization for the latch is deprecated. For the C3T the ESP-IDF was recommended in order to optimize the boot up time.

There are software examples on the documentation page.

Hand made in germany

All the Picoclicks are assembled, soldered, inspected and tested in my little maker lab by myself here in germany.

Order contains and battery shipping restrictions

• 1pcs bare Picoclick-C3 development board (without battery and case)
• (Optional) FPC breakout board
• (Optional) FPC cable 5cm for connecting the FPC breakout board or an extension board
• (Optional) FPC cable 10cm for connecting the FPC breakout board or an extension board

Unfortunately, it is not possible for me to provide a complete set with a fitting tiny LiPo battery included. If you're looking for a good one, then make sure it is a 301010 or a 401010 one. For further battery informations, please check the documentation/Github.

Video of the Picoclick C3

The video shows the journey of the Picoclicks as well as the assembly of the C3 and what it can be used for.