The Maple runs at a maximum of 72 MHz, has 39 digital input/output pins, 16 analog inputs, native full speed USB, 3 USARTs (hardware serial ports), integrated SPI/I2C support, a power jack, and a reset button.

Features:

• Microcontroller: STM32 F103RB
• Clock Speed: 72 MHz
• Operating Voltage: 3.3V
• Input Voltage (recommended): 3.0V-18V
• Digital I/O Pins: 39
• Analog Input Pins: 16
• Flash Memory: 128 KB
• SRAM: 20KB
• 64 Channel nested vector interrupt handler (including external interrupt on GPIO’s)
• Integrated SPI/I2C and 7 Channels of Direct Memory Access (DMA)
• Supplies up to 800mA @ 3.3v
• Support for low power and sleep modes (<500uA)
• Dimensions: 2.05″x2.1″