Open Data Acquisition System

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Block Diagram

The Open Data Acquisition System consists of a Data Acquisition Processor (DAP) and up to 8 I/O cards.

The block diagram is:

ODAS Block Diagram.png

Features

The Open Data Acquisition System features a powerful combination of Open Hardware and Open Software to access low level hardware interfaces from a Host Computer.

Open Hardware

Open Software

  • USB Interface runs industry standard Firmata
  • Processor card runs Arduino Leonardo compatible software
  • Arduino "Wire" Standard I2C bit driver
  • Community supported Python, C++, Ruby, LabView, VxWorks drivers

Host Software - Firmata

Firmata is a generic protocol for communicating with microcontrollers from software on a host computer. It is intended to work with any host computer software package. Right now there is a matching object in a number of languages. It is easy to add objects for other software to use this protocol. Basically, this firmware establishes a protocol for talking to the Arduino from the host software. The aim is to allow people to completely control the Arduino from software on the host computer.

Firmata has an attractive Test Program User Interface which could be easily extended

Firmata_test_screenshot.png

Personality EEPROM

struct eep_vals
{
  char signature[4]; // "ODAS" in ASCII
  byte fmt_version;  // EEPROM data format version (0x00 reserved, 0x01 = first version)
  byte rsvd;         // set to 0
  short numatoms;    // set to 2
  long eeplen;       // set to 96 dec
  char uuid[16];     // "0000000000000000" in ASCII
  short pid;         // See PID table
  char vslen;        // set to 32 dec
  char pslen;        // set to 32 dec
  char vstr[32];     // Vendor Null terminated String
  char pstr[32];     // Product Null terminated String
};

Product ID Table

Signature=ODAS
Vendor=land.boards.com
ProductID (in hex) Product (string)
1 DIGIO16-I2C
2 DIGIO128
3 OptoIn8-I2C
4 OptoOut8-I2C
5 DIGIO32-I2C
6 PROTO16-I2C
7
8
9

Drivers

Arduino

Raspberry Pi

lsmod dump with DIGIO-128 card attached

pi@raspi3 ~ $ lsmod | grep i2c_
i2c_dev                 5557  0
i2c_bcm2708             3997  0
pi@raspi3 ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 21 22 23 24 25 26 27 -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Raspberry Pi Performance with DIGIO-128 card attached

  • sudo python Adafruit_MCP230xx.py
  • Clock runs at 100 KHz

RPi-I2C-DIGIO-128-clk-data.png

  • Overall timing - 1 cycle

RPi-I2C-DIGIO-128-overall-read-1cycle.png

  • Overall timing - 2 cycle (Read-modify-write)

RPi-I2C-DIGIO-128-overall-rmw-2cycles.png

Cards

Optically Isolated cards are necessary to connect together different electrical system without concerns for ground loops, voltage dropes or electrical noise. ODAS offers two optically isolated cards; one for input and one for output.

Digital I/O

No Data Acquistion System is complete without a Processor Card.

  • DAS-32U4 - Data Acquisition System Processor DAS-32U4

ODAS Card Test Station

  • ODAS Test Station
  • ODAS Tester - Test Software in GitHub repository
  • Arduino Nano
  • Cables or loopback connector
  • Auto-detect card if test has been run before
  • Presents card type list for un-programmed EEPROMs
Checking EEPROM for board type...Detected DIGIO-128 board
R=Read EEPROM, W=Write EEPROM, T=Test DIGIOs, L=Loop Test, B=Bounce LEDs