Challenger+ T3217

ATtiny3217 Development Board

The Challenger T3217 is a compact and versatile development board built around the Microchip ATtiny3217 microcontroller. Designed in the proven Challenger+ form factor, it combines robust performance, full pin accessibility, and modern USB Type-C connectivity in a small, reliable package.

At its core, the ATtiny3217 delivers modern 8-bit processing performance with 32 KB of Flash, 2 KB of SRAM, and 256 bytes of EEPROM, offering an ideal balance between capability and efficiency. With rich peripheral support including a 10-bit ADC, 8-bit DAC, multiple 16-bit timers, USART, SPI, and I²C interfaces the device is well suited for both simple and advanced embedded applications.

All but one (The last one being connected to the on board LED) of the microcontroller’s I/O pins are made available through the Challenger+ dual header connectors, ensuring straightforward access to every peripheral and function pin. This makes the Challenger T3217 an excellent platform for low-level hardware development, education, and integration into larger systems.

Key Features

• Microcontroller: Microchip ATtiny3217 (8-bit AVR® core, 20 MHz internal oscillator)
• Memory: 32 KB Flash / 2 KB SRAM / 256 B EEPROM
• I/O: All 20 I/O pins fully accessible via Challenger+ header connectors
• Interfaces: 1× USART, 1× SPI, 1× I²C, 10-bit ADC, 8-bit DAC, timers, comparator, event system
• USB Connectivity: USB Type-C interface with CH340B USB 2.0 to UART transceiver
• Bootloader: Pre-installed Optiboot for firmware upload via USB
• Battery Support: Built-in Li-Po charger and 2-pin battery 1.25mm pitch connector for portable operation
• Operating Voltage: 3.3 V logic level (USB or Li-Po powered)
• Form Factor: Challenger+ standard (compatible with Challenger accessories and expansion boards)
• Dimensions: 50.8 mm × 22.86 mm (Feather-compatible outline)
• Weight: ≈ 9 g

Short introduction to the board

PCB
The Challenger+ board format is based on a popular form factor called “Feather” created and maintained by an American company called Adafruit. The entire specification for the Feather format is available here. The size of the PCB for the module is 50.80mm x 22.86mm but the entire module is a little bit bigger as the Type C USB connector protrudes about 1 mm outside the board. The Challenger+ uses another much smaller battery connector to allow the board to be integrated in more confined spaces.

Headers
On each of the longer sides of the PCB there are holes intended for soldering pin header connectors. If you don’t want to use connectors for some reason you can also solder a wire directly into the hole, making a permanent connection to your external device. If you go this way please make sure that the wires are fixed in place, otherwise vibrations can cause the wire to brake at the soldering point.

BConnect
The BConnect interface is a compact 4-pin connector designed by iLabs to provide a simple and reliable link between the Challenger+ board and compatible expansion modules. It carries power, ground, and UART/I2C communication signals, allowing for both data transfer and power delivery through a single flat flex cable. The connector uses a low-profile design to ensure secure and correct insertion, making it ideal for compact or embedded applications.

The Challenger T3217 board implements both a sink and the source connector which allows you to operate it both as a BConnect I2C master and a I2C slave. Using SoftwareSerial you can of course also implement connections to BSerial compatible modules.

LED’s
On each side of the USB connector there is a small indicator LED placed. The LED which is marked CHG is the charge control indicator. This red LED will shine whenever the connected battery is being charged, and when the battery is fully charged the LED will turn off again. If you haven’t connected a battery to the board this LED will not come on at all.

On the other side of the USB connector there is a user programmable green LED. This LED is connected to pin PIN_PA6 and can easily be controlled by the user program.