Orbit BoosterPack Reference Manual

This module is no longer manufactured, sold, or supported by Digilent. All available resources, including PCB design files, are freely available on the Orbit BoosterPack Resource Center, courtesy of Digilent and the Cosmiac group at the University of New Mexico.

The Digilent Orbit BoosterPack is an add-on board for the Texas Instruments® Stellaris and Tiva™ C Series LaunchPad microcontroller evaluation kits. The Orbit greatly expands the input/output capabilities of the LaunchPad, as well as introducing Digilent Pmod expansion connectors.


  • Greatly expands the I/O capabilities of your Tiva LaunchPad kit
  • Two 1×6 Digilent Pmod connectors
  • 3-axis accelerometer
  • I2C temperature sensor
  • 128×32 pixel OLED display
  • Analog potentiometer
  • 256 Kbit I2C EEPROM

1. Orbit BoosterPack Hardware Description

The following gives a basic description of the input/output hardware contained in the Orbit BoosterPack and how to use it. Refer to Appendix A for a table showing pin definitions.

1.1. OLED Graphic Display

The Orbit board provides a 128×32 pixel, organic LED (OLED), graphic display panel. The graphic display panel used is the WiseChip/Univision UG-23832HSWEG04. This display uses the Soloman Systech SSD1306 display controller.

The UG2832 has a power on/power off sequence that should be followed. Failure to follow the power on/power off sequence can shorten the life of the display. The Orbit provides two FETs for software control of the two power supplies for the display. The VDD_OLED control is used to turn on/off the power to the logic of the display. The VBAT_OLED control is used to turn on/off power to the OLED display itself. These two pins have pull-up resistors to turn off their respective power supplies when not being driven. The pins are made to be outputs and are driven low to turn on the power supplies.

Power on sequence: Apply power to VDD Send Display Off command Initialize display to desired operating mode Clear screen Apply power to VBAT Delay 100ms Send Display On command

Power off sequence: Send Display Off command Power off VBAT Delay 100ms Power off VDD

The display has a D/C pin (display or command select) that is used to determine whether bytes sent to the display are interpreted as commands or as display data. The D/C pin is driven high for display buffer access and is driven low for command access. This pin is shared with VBUS detection on the LaunchPad. If VBUS is present, the pull-down resistor acts as a pull-up resistor in conjunction with resistor 6 (R6) on the LaunchPad. Please see the note in the Orbit BoosterPack Schematic available from the Orbit BoosterPack Resource Center.

The D/C pin is also a non-maskable interrupt (NMI) pin on the LaunchPad, and is “locked” on the device's power-up. In order to unlock the D/C pin to be used as a general purpose output, 0x4C4F434B must be written to GPIOLOCK register. For more information, please see the LM4F120H5QR Datasheet at: www.ti.com.

The RES pin is used to reset the SG1306 display controller. The RES pin is driven low for reset and driven high for normal operation. The low-going reset pulse must be a minimum of 3μs (microseconds) for the display controller to reset correctly.

The UG2832 is a serial device that is accessed using SPI. It is however, a write-only device. It is not possible to read back either the display buffer contents or any kind of status from the panel. The maximum SPI clock frequency supported by the UG2832 is 10 MHz.

Digilent has a library for use with the Orbit BoosterPack that provides functions for initializing the display and rendering simple text and graphics onto the display. This library can be used as is or as a starting point for a more sophisticated graphics library and is available in the Orbit BoosterPack Resource Center.

1.2. Digilent Pmod Connectors

Two 1×6 pin female Digilent Pmod connectors are provided for functional expansion of the Orbit BoosterPack. They are labeled JA and JB respectively. Header JA has signals routed to the Synchronous Serial Interface (SSI) peripheral on the LaunchPad. These signals can be used with Pmods that use standard 3 or 4 wire SPI communication protocol.

1.3. Discrete Digital I/O Devices

Pushbuttons: There are two pushbutton switches labeled BTN1 and BTN2. A read to the corresponding GPIODATA register bits will return a '0' when the button is released and a '1' when the button is pressed.

Slide Switches: There are two slide switches labeled SW1 and SW2. A read to the corresponding GPIODATA register bits will return a '0' when a switch is down (toward the LEDs) and a '1' when a switch is up (toward the OLED display).

LEDs: There are four LEDs, labeled LD1 – LD4. An LED will be illuminated when the corresponding GPIODATA register bit is set to a '1' (given the corresponding direction bit has been set in the GPIODIR registers) and off when set to a '0'.

1.4. I2C Bus

The I2C bus from the LaunchPad microcontroller board is brought onto the Orbit BoosterPack. There are three I2C devices on the board: a 256 Kbit EEPROM, a temperature sensor, and an accelerometer. In addition, there is a connector for taking the I2C bus off of the board to connect to additional external I2C devices.

I2C Connector: Connector J5 can be used to extend the I2C bus off of the board to connect to additional external I2C devices. J5 is a standard 2×4 pin header connector with 0.100” spaced pins. It provides access to the I2C signals, SCL and SDA, plus VCC3V3 and GND. The VCC3V3 can be used to power external I2C devices.

The I2C bus uses open collector drivers to allow multiple devices to drive the bus signals. This means that pull-up resistors must be provided to supply the logic high state for the signals. The Orbit BoosterPack provides 2.2 K-ohm pull-up resistors. Generally, only one set of pull-up resistors are used on the bus.

Digilent has several small I/O modules available that can be connected using the I2C connector. These include a 4-channel, 12-bit A/D converter, serial character LCD panel, 3-axis gyroscope, real-time clock/calendar, and I/O expander.

EEPROM: A 256Kbit (32Kbyte), I2C EEPROM is provided using a Microchip 24LC256. This EEPROM, IC3, is located on the bottom side of the board.

The seven bit I2C device address for the EEPROM is '1 0 1 0 A2 0 0', where A2 is an external pin. Pin A2 is pulled high through a 10 K-ohm resistor and a cuttable trace at JP7. Therefore, the 'as-is' seven bit I2C device address for the EEPROM is '1010100', or 0x54. Cutting the trace between pins 1 and 2 of JP7 and loading a two-pin header with a shorting block on pins 2 and 3 of JP7 will make the 10 K-ohm resistor acts as pull-down. In this case, A2 must be set to '0' in software.

For complete technical documentation on the 24LC256, refer to the data sheet available from www.microchip.com.

Temperature Sensor: A digital temperature sensor is provided using a Microchip TCN75A 2-Wire Serial Temperature Sensor. The temperature sensor, IC4, is an I2C device, and is located next to BTN1.

The TCN75A is rated for an accuracy of +/-1ºC and has selectable resolution from 0.5ºC down to 0.0625ºC. The seven bit device address is '1001111', or 0x4F. Note that the last three bits set to '1' because external pins A2, A1, and A0 are pulled high by 10 K-ohm resistors and cuttable traces at JP2, JP4, and JP6.

The TCN75A provides an alert output that can be programmed for various functions.

For complete technical documentation on the TCN75A, refer to the data sheet available at www.microchip.com.

Accelerometer: A 3-axis accelerometer is provided using an Analog Devices ADXL345. This accelerometer, IC2, is located to the right of BTN2. The silkscreen shows the axis configuration.

The 7 bit I2C device address for the accelerometer is '0011101', or 0x1D.

The ADXL345 has two output pins for setting configurable interrupts, which include activity, inactivity, and DATA_READY.

For complete technical documentation on the ADXL345, refer to the data sheet available at www.analog.com.

1.5. Potentiometer

A potentiometer (pot) is provided on the board to be used as an analog signal source or analog control input. The pot is a 1 K-ohm trimmer pot connected between the VCC3V3 supply and ground. The wiper of the pot is connected to analog input AIN0.

Appendix A: Orbit BoosterPack Pinout Table

Connector # Pin # Port and Bit Function Description Notes
J1 1 - VCC3V3 Power supply
J1 2 PB5 LD4 User LED
J1 3 PB0 JB_03/RX Pmod connector B pin 3/Rx UART1
J1 4 PB1 JB_02/TX Pmod connector B pin 2/Tx UART1
J1 5 PE4 INT2_ACL Accelerometer Interrupt Output
J1 6 PF5 /RES_OLED OLED reset
J1 7 PB4 INT1_ACL Accelerometer Interrupt Output
J1 8 PA5 JA_02/MOSI Pmod Connector A pin 2/Serial Out SSI0
J1 9 PA6 SW2 Slide switch
J1 10 PA7 SW1 Slide switch
J2 1 - GND Ground
J2 2 PB2 SCL I2C clock I2C0
J2 3 PE0 BTN2 Push button
J2 4 - - - Not connected
J2 5 - - - Not connected
J2 6 - - - Not connected
J2 7 - - - Not connected
J2 8 PA4 JA_03/MISO Pmod Connector A pin 3/Serial In SSI0
J2 9 PA3 JA_01/SS Pmod Connector A pin 1/Slave Select SSI0
J2 10 PA2 JA_04/SCK Pmod Connector A pin 4/Serial Clock SSI0
J3 1 - - - Not connected
J3 2 - GND Ground
J3 3 PD0 SCK_OLED OLED serial clock SSI3/SSI1
J3 4 PD1 /CS_OLED OLED chip select SSI3/SSI1
J3 5 PD2 BTN1 Push button
J3 6 PD3 SDI_OLED OLED serial data in SSI3/SSI1
J3 9 PE3 AIN Potentiometer AIN0
J3 10 - - - Not connected
J4 1 - - - Not connected
J4 2 - - - Not connected
J4 3 PB3 SDA I2C data I2C0
J4 4 PF0 JB_04/RTS Pmod connector B pin 4/Request to Send UART1
J4 5 PF1 JB01/CTS Pmod connector B pin 1/Clear to Send UART1
J4 6 PC6 LD1 User LED
J4 7 PC7 LD2 User LED
J4 8 PD6 LD3 User LED
J4 9 PD7 /DC_OLED OLED data/command select
J4 10 - Not connected