2. Connections to the mbed LPC1768

The mbed LPC1768 has 40 user-accessible pins, but not all of those are available when it is integrated into a Flight Computer. Some pins are connected via the PCB to parts of the Flight Computer (SD card interface, XBee radio, and LEDs on the external interface), a few pins are left without connections, and the majority of the pins are accessible to the user.

On the standard flight computer, user-accessible mbed pins are routed to sets of header sockets immediately adjacent to the breadboard. Jumper wires can connect these to the breadboard or to an exterior set of header sockets. The exterior header sockets are linked to corresponding screw terminals on the edge of the PCB. These screw terminals provide a convenient and secure way to make connections to external components.

On the mini Flight Computer, user-accessible mbed pins are routed directly to screw terminals.

Pins routed to Flight Computer components

Pin	Function	Connection	Shared with user?
p1	ground (0 V)	GND	Y
p2	VIN	LiPo battery	N
p5	SPI MOSI	SD card interface	Y
p6	SPI MISO	SD card interface	Y
p7	SPI SCK	SD card interface	Y
p8	GPIO	SD card (chip select)	N
p21	DigitalOut	external interface (LED A)	N
p22	DigitalOut	external interface (LED B)	N
p23	DigitalOut	external interface (LED C)	N
p26	DigitalOut	XBee radio reset	N
p27	Serial Rx	XBee radio Tx	N
p28	Serial Tx	XBee radio Rx	N
p40	power (3.3 V)	VOUT	Y

Pins reserved for user. All can be GPIO or the additional function(s) shown.

Pin	Function	Block Label on Standard
p9	Serial Tx or I2C SDA	I2C
p10	Serial Rx or I2C SCL	I2C
p11	SPI MOSI	no label
p12	SPI MISO	no label
p13	Serial Tx or SPI SCK	Serial
p14	Serial Rx	Serial
p15	AnalogIn	Analog
p16	AnalogIn	Analog
p17	AnalogIn	Analog
p18	AnalogOut or AnalogIn	Analog
p19	AnalogIn (no interrupts)	Analog
p20	AnalogIn (no interrupts)	Analog
p24	PwmOut	PWM
p25	PwmOut	PWM
p29	CAN	CAN
p30	CAN	CAN