By Jeremy Seiden (Mission, Systems, and Test)

I walk through the interface definitions for the project.

Introduction

Below is the table containing the interface definitions for the 2016 SPARCCS instrument, as well as an explanation of the major subsystem interfaces. This table clearly distinguishes the connections between subsystem hardware present on the instrument. The columns represent the present subsystems. If any values share a row, that denotes a connection. In the ATmega32U4 column, the numbers on the left of the column represent the pins of the micro-controller chip.  See the system block diagram for subsystem explanations.

PC- 104	ATmega32U4		AVR SPI Header	USB Port	Transceivers (1 & 2)	DB9 Connector	LND 712 Geiger Counter	A06N-5 DC-DC converter	UcamII
	1	PE6 (INT.6/AIN0)
VCC	2	UVcc
	3	D-		D-
	4	D+		D+
GND	5	UGnd
	6	UCap
	7	VBus		VBus
	9	PB1 (PCINT1/SCLK)	SCK
	10	PB2 (PDI/PCINT2/MOSI)	MOSI
	11	PB3 (PDO/PCINT3/MISO)	MISO
	12	PB7 (PCINT7/OC0A/OC1C/)			DI (1)
RST	13		RST
VCC	14	VCC	VCC		VCC
GND	15	GND	GND	GND	GND		GND
	16	XTAL2
	17	XTAL1
	18	PD0 (OC0B/SCL/)					OUT
	20	PD2 (RXD1/)			RO (2)
	21	PD3 (TXD1/)			DI (2)
	22	PD5 (XCK1/)			RO (1)
GND	23	GND
VCC	24	AVCC
	31	PC6 (OC3A/)							RxC
	32	PC7 (ICP3/CLK0/OC4A)							TxC
VCC	34	VCC				VCC		(+)IN	5V
GND	35	GND						(-)IN	GND
VCC	42	AREF
GND	43	GND						HVRTN
VCC	44	AVCC
							VCC	HVOUT
					Z (2)	TX-
					Y (2)	TX+
					Y (1)	RTS-
					Z (1)	RTS+
					B(2)	RX-
					A(2)	RX+
					A(1)	CTS-
					B(1)	CTS+

 

Interface Explanation

Supply voltage (Vcc) and ground (GND) connections can be found on components supplied from the PC-104 bus connection. SPI headers and USB port are connected to ATMega32U4 to allow interface with computer for bootloading. RS-422 Transceivers are connected to pins 20-22 of the ATMega32U4 and from there to the DB9 connector pinout for connection to computer. The UCamII occupies pins 31 and 32 for serial communication with the microcontroller, as well as a 5V and a ground connection. The Geiger tube output is connected to pin 18 to record events detected by the LND-712 Geiger Tube.