The touch board is a microcontroller board with dedicated capacitive touch and MP3 decoder ICs. It has a headphone socket and micro SD card holder (for file storage), as well as having 12 capacitive touch electrodes. It is based around the ATmega32U4 and runs at 16MHz from 5V. It has a micro USB connector, a JST connector for an external lithium polymer (LiPo) cell, a power switch and a reset button.

It is similar to the Arduino Leonardo board and can be programmed using the Arduino IDE. The ATmega32U4 can appear to a connected computer as a mouse or a keyboard, (HID) serial port (CDC) or USB MIDI device

Note: The Micro SD card has been used for illustration purposes and is not supplied with the board.

• Data Sheet – Touch Board vs Pi Cap
• Data Sheet – Touch Boards and shields
• Data Sheet – Touch Boards pin map
• Data Sheet

Specifications

• Microcontroller Atmel ATmega32U4
• Touch IC Resurgent Semiconductor MPR121
• MP3 decoder IC VLSI Solution VS1053b
• Audio output 15mW into 32 via 3.5mm stereo socket
• Removable storage up to 32GB via micro SD card
• Input voltage 3.0V DC 5.5V DC
• Operating voltage 5V DC
• Max. output current (5V rail) 400mA (100mA at startup)
• Max. output current (3.3V rail) 300mA
• LiPo cell connector 2-way JST PH series – pin 1 +ve, pin 2 -ve
• LiPo charge current 200mA
• Capacitive touch electrodes 12 (of which 8 can be configured as digital I/O)
• Digital I/O Pins 20 (of which 3 are used for the MPR121 and 5 are used for the VS1053b the latter can be unlinked via solder blobs)
• PWM channels 7 (shared with digital I/O pins)
• Analogue input channels 12 (shared with digital I/O pins)
• Flash memory 32 kB (ATmega32U4) of which 4kB used by boot loader
• SRAM 2.5kB (ATmega32U4)
• EEPROM 1kB (ATmega32U4)
• Clock speed 16MHz (ATmega32U4), 12.288MHz (VS1053b)
• DC current per I/O pin 40mA sink and source (ATmega32U4), 12mA source / 1.2mA sink (MPR121)
• Analogue input resistance 100M typical (ATmega32U4)