Hardware/CubeSat Gumstix
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Revision as of 15:57, 12 October 2015
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This board is the result of a diploma work. It is meant to be a first evaluation version of a Cubesat image processing board.
Type | FPGA Rack | Schematic | UCF | Description |
---|---|---|---|---|
2015 | ![]() |
FPGA + Gumstix 2015 schematic top view |
FPGA + Gumstix 2015 UCF | FPGAs: Spartan 6 XC6SLX45, XC6SLX100 or XC6SLX150 SPI flash: M23P64-ME |
Components
Camera
The 24-pin camera interface connector is foreseen to be used with different camera models.
It has:
- a 3.3 V power supply
- 2 serial control lines
- 4 framing lines
- 12 data lines
- 4 camera control lines
ADC
The board hosts a ADS8028 12-bit, 1 MSPS, 8-channel analog-to-digital converter.
The ADC is powered with the input 5 V for the analog part and with a local 3.3 V for the digital lines. The voltage reference input connects to the analog power supply via jumper J5.
Inputs AIN0 to AIN4 are used to monitor the board's power supplies. Inputs AIN5 to AIN7 are sourced by connector J9.
The connection to the FPGA is given in the following table:
ADC signal |
FPGA pin |
function |
---|---|---|
CS_n | C16 | chip select, active low |
SCLK | B12 | serial clock |
DOUT | A18 | slave out (MISO) |
DIN | C17 | slave in (MOSI) |
PD_n_RST_n | B18 | power down or restart, active low |
TM_BUSY | A17 | busy aquiring temperature |
Gumstix
A Gumstix board can be plugged onto the CubeSat board. It is provided for the image processing tasks. When using a Gumstix, the FPGA bank 2 must be powered with 1.8 V.
The Gumstix connector could be used for other purposes such as adding external RAM to the FPGA.
Console
The processor's serial console, UART 3, is connected to a micro-USB connector on the side of the board via an FTDI USB-UART interface.
UART
The Gumstix UART 1 connects to the FPGA. Two test points allow to monitor these signals and check the logic levels of the Gumstix to FPGA lines. Achieved data rates range up to xxx kbit/sec.
The connection is given in the following table:
Gumstix signal |
FPGA pin |
function |
---|---|---|
TxD1 | V21 | Gumstix TxD out |
RxD1 | C22 | Gumstix RxD in |
SPI
The Gumstix acts as a master of an SPI link to the FPGA. Achieved data rates range up to xxx Mbit/sec.
The connection is given in the following table:
Gumstix signal |
FPGA pin |
function |
---|---|---|
CS_0 | W22 | chip select, active ? |
SCLK | H21 | serial clock |
MOSI | B22 | Gumstix out, FPGA in |
MISO | A21 | Gumstix in, FPGA out |
Extended memory bus
The Gumstix extended memory bus, with 10 address and 15 data bits, is also connected to the FPGA. This should allow very high data rates, but hasn't been tested yet.
Reset
The reset pin is connected both to a press button and a pull-up resistor.
OBC connectors
Two 22-pin Else spring-loaded connectors are used to connect to the On-Board Computer (OBC). Connector B allows to use differential signalling, as it is the case for SpaceWire.
The connection to the FPGA I/O is given in the following table:
connector pin |
FPGA pin connector A |
FPGA pin connector B |
diff. pair |
---|---|---|---|
1 | Y4 | Y18 | |
2 | W3 | W18 | |
3 | Y7 | AA2 | 10 p |
4 | V7 | AB2 | 10 n |
5 | Y8 | AA4 | 9 p |
6 | W8 | AB4 | 9 n |
7 | Y9 | AA6 | 8 p |
8 | W9 | AB6 | 8 n |
9 | Y10 | AA8 | 7 p |
10 | W10 | AB8 | 7 n |
11 | W11 | AA10 | 6 p |
12 | V11 | AB10 | 6 n |
13 | Y12 | AA12 | 5 p |
14 | W12 | AB12 | 5 n |
15 | Y13 | AA14 | 4 p |
16 | W13 | AB14 | 4 n |
17 | Y14 | AA16 | 3 p |
18 | W14 | AB16 | 3 n |
19 | Y15 | AA18 | 2 p |
20 | V15 | AB18 | 2 n |
21 | Y17 | AA21 | 1 p |
22 | W17 | AB21 | 1 n |
Peripheral connectors
Two 24-pin peripheral connectors are provided. Both comprise 2 power supply pins and 22 FPGA I/O:
connector pin |
FPGA pin peripheral 1 |
FPGA pin peripheral 2 |
---|---|---|
1 | 3.3 V | 3.3 v |
2 | GND | GND |
3 | Y1 | L1 |
4 | Y2 | L3 |
5 | W1 | K1 |
6 | W3 | K3 |
7 | V1 | J1 |
8 | V3 | J3 |
9 | U1 | H1 |
10 | U3 | H3 |
11 | T2 | H2 |
12 | T4 | H4 |
13 | T1 | G1 |
14 | T3 | G4 |
15 | R1 | F1 |
16 | R4 | F3 |
17 | P1 | F2 |
18 | R3 | F5 |
19 | N1 | E1 |
20 | N3 | E3 |
21 | M2 | D1 |
22 | M4 | D3 |
23 | M1 | D2 |
24 | M3 | D5 |
Power supplies
The board receives a 5 V power input. 4 DC/DC converters provide power for different components.
FPGA supply
On the FPGA:
- VCC33 is used by the FPGA for VCCAUX, the SPI flash, the JTAG connector, bank 0 and bank 3
- VCC18/33 is used for FPGA bank 1
- VCC25/33 is used for FPGA bank 2
- VCC12 is used for the FPGA core
Bank 0 connects to the camera and the ADC
Bank 1 is connected to the Gumstix and 1.8 V should be used. The Gumstix board could be replaced by a memory board which might require 3.3 V signalling
Bank 2 connects to the On-Board Computer (OBC). The OBC connector B allows to have SpaceWire differential lines. If so, one has to mount the 165 Ω serial and 140 Ω parallel resistors. Normal CMOS signalling requires 0 Ω serial and no parallel resistors.
Bank 3 connects to the spare connectors on the side of the board.
Test designs
ADC controller
The ADC controller design reads the 8 ADC channels together with the temperature value and sends the values to the serial port.
The serial data out is provided on xxx.
Forhe serial data is mirrored on the peripheral 2 connector. Connect a serial port cable to this connector:
- GND pin 2
- RxD pin 4
The FTDI serial-USB adapter uses:
- GND: black
- TxD: orange
- RxD: yellow