Orbit BoosterPack™ Reference Manual
Revised June 5, 2013
This manual applies to REV A of the board.
The Digilent Orbit BoosterPack is an add-on board for the Texas Instruments™ Stellaris® LaunchPad microcontroller evaluation kit. The Orbit greatly expands the input/output capabilities of the LaunchPad, as well as introducing Digilent Pmod™ expansion connectors.
- Two 1×6 Digilent Pmod™ connectors
- 3-axis accelerometer
- 256 Kbit I2C EEPROM
- I2C temperature sensor
- 128×32 pixel OLED display
- Analog potentiometer
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 www.digilentinc.com.
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 at www.digilentinc.com.
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.
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||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||7||PB4||INT1_ACL||Accelerometer Interrupt Output|
|J1||8||PA5||JA_02/MOSI||Pmod Connector A pin 2/Serial Out||SSI0|
|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||3||PD0||SCK_OLED||OLED serial clock||SSI3/SSI1|
|J3||4||PD1||/CS_OLED||OLED chip select||SSI3/SSI1|
|J3||6||PD3||SDI_OLED||OLED serial data in||SSI3/SSI1|
|J3||7||PF1||VBAT_OLED||OLED VBAT enable|
|J3||8||PE2||VDD_OLED||OLED VDD enable|
|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||9||PD7||/DC_OLED||OLED data/command select|