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Hannah Development Board

Hannah is a development board for the hobbyist with many useful peripherals on board.

Note The Hannah is not a great ‘first board’ to learn on as most of the functionality is hidden behind various I²C devices, including the buttons and RGB LED.


Power can be supplied using a USB Mini-B cable from a USB Charger or standard USB Port, though the data lines are not connected to anything. Optionally, four AA batteries may be fitted to the carrier on the rear side of the board. You may select between USB power and battery power by placing a shunt on the power select header. Please note that Hannah does not have any circuitry for charging a battery and you should never short USB power to the battery pack.


Hannah has on board:

  • Rotary Potentiometer
  • 2x Push Buttons
  • RGB Light Sensor
  • Temperature Sensor
  • 3-axis Accelerometer
  • Hall Sensor
  • 2x Servo Output

External Signals

Hannah bring out the following signals to pads:

  • 5x GPIO
  • I²C Bus (3.3v signal levels)
  • Clock
  • 3.3V and Ground

0.1-inch pitch SIL headers may be fitted if required.


Clearly Hannah boasts many more peripherals than could be directly connected to the six general purpose pins of an imp. This is achieved through use of an I²C bus and an IO expander. The imp's pins are assigned as follows:

Pin Mode Description
Pin 1 Digital input Interrupt from GPIO expander
Pin 2 Analog input Potentiometer wiper
Pin 5 Digital output Servo port 1 PWM signal
Pin 7 Digital output Servo port 2 PWM signal
Pin 8 I2C SCL I2C Bus
Pin 9 I2C SDA I2C Bus

The IO expander pins are assigned as follows:

Pin Mode Description
IO0 Input Button 1
IO1 Input Button 2
IO2 Input Hall Switch
IO3 Input Accelerometer interrupt
IO4 Input Temperature sensor alert interrupt
IO5 Output RGB LED Green
IO6 Output RGB LED Blue
IO7 Output RGB LED Red
IO8 Output Potentiometer enable
IO9 Output RGB light sensor sleep
IO10 Output Server ports 1 and 2 power enable
IO11 GPIO Spare
IO12 GPIO Spare
IO13 GPIO Spare
IO14 GPIO Spare
IO15 GPIO Spare

The I²C bus has the following on-board peripherals:

8-bit Address 7-bit Address (do not use) Part No Description
0x38 0x1c LIS331DL 3-axis accelerometer
0xE8 0x74 ADJD-S311-CR999 RGB Light Sensor
0x98 0x4C SA56004ED Temperature sensor
0x7C 0x3E SX1509BULTRT IO Expander

Hardware Design Files