SREEB - Simple Research Equipment Extension Box

Control external scientific equippment using the Arduino-based Robot Controller Shield by Watterott (https://github.com/watterott/Robot-Controller/).

The software sets up a simple communication protocol that can be extended by the user (see libraries/RMsg). The client sends commands or requests as ASCII strings via the serial/USB connection to the Arduino controller (the host), which acknowledges the command or replies by sending data.

Commands or requests always have the form:

>CMD A=d1,d2,d3... B=d4,d5,...;

with > indicating the start and ; the end of a command, CMD the command token, A, B, ... optional parameters with d1, d2, ... numerical data values (16-bit integers).

The reply from the controller (host) starts with a < and ends with ; like client commands/requests. The controller can reply to three ways: by acknowledging the command/request (ACK), by returning an error (ERR), or by returning data (in this case the returned token is the same as the command token, see e.g. VER below).

• Returning an error code regarding the last message

  <ERR C=x E=y,z;

  with x, command index (255=not recognized), y, error code, and z, error value (further specifies the error).

• Acknowledging that command has been executed; when no error occurred and the command has no specific response message defined (other than e.g. >VER;)

  <ACK C=x;

  with x, command index

Currently available commands:

• Information about software version (V) and free space in SRAM (M) in bytes

  >VER;

  Returns something like:

  <VER V=100 M=1234;

• Define a servo port, two servo positions and a port that serves as input to toggle between these two servo positions.

  >SDT P=s,i,o S=a,b;

  with s, servo port index (1...8) as output to servo, i, servo port index (1...8) as input to toggle servo, o, servo port index (1...8) as output to indicate servo position "a", a and b, two servo positions (0...255) for the signal at i being LOW or HIGH, respectively.

• Define I/O mode of up to 8 digital pins (=servo ports).

  >SDM P=x1,x2... M=y1,y2...;

  with x1,.., servo port index (1...8), y1,.. modes (0=input, 1=input_low, 2=output, 3=servo). Note that mode == 0 (input) requires an external pulldown resistor, whereas mode == 1 (iput low) uses the internal 2k pullup resistor.

• Set up to 8 digital pin (=servo ports) values simultanously.

  >SDV P=x1,x2... V=y1,y2...;

  with x1,.. servo port index (1...8), y1,..values. For output pins, 0=low, 1=high, and for servo pins, 0..255 as angular position.

• Clear all settings.

  >CLR;