Hardware/CubeSat Gumstix/Test/ADC

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The ADC controller design reads the 8 ADC channels together with the temperature value and sends the values to the serial port.

The UART baud rate is 115˙200. The ADC sampling rate is 100 Hz, due to the slow UART text transmission. The ADC's SPI connection runs at 12.5 MHz (100 MHz / 4 / 2).

SPI

The ADC's SPI interface is mirrored on the peripheral 2 connector:

  • CS_n pin 5
  • SCLK pin 6
  • MOSI pin 7
  • MISO pin 8
  • RST_N pin 9
  • BUSY pin 10

Serial port

The serial data out is provided on the serial port to the Gumstix. It is mirrored on the peripheral 2 connector:

  • GND pin 2
  • TxD pin 3 (not used)
  • RxD pin 4

The FTDI serial-USB adapter uses:

  • GND: black
  • TxD: orange
  • RxD: yellow

Measurements

With a 5 V voltage reference, the reading should be:

  • FFFh for the 5 V on channel 0
  • A8Fh for the 3.3 V on channels 1 to 3
  • 800h for the 2.5 V on channel 1
  • 5C2h for the 1.8 V on channel 2
  • 3D7h for the 1.2 V on channel 4

Gumstix

Log-in to the Gumstix via the USB serial console with administrative rights.

List the possible serial ports:

ls -l /dev/tty*
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