Listing1
The connection takes into account that the microcontroller’s TX line is connected to OMC21’s RX line and, if the reading of the voltage supply is requested, that the microcontroller’s RX line is connected to OMC21’s TX line as well. The code line that enables this serial port is Serial1.begin(9600); even in this case the communication speed can be set up to a maximum of 115.200 bps. As for the rest of the management from the point of view of the software, it is the same of the main serial port. As for the I²C communication port, it is enabled by means of the Wire.onReceive(I2CreceiveEvent) instruction, in which the I2CreceiveEvent label indicates the procedure recalled by the interrupt, when the first byte arrives. Please refer yourself to the Listing 2, for the particulars concerning the processing of the data received.
Listing2
For each data arrived on this port, a procedure is recalled: it deals with checking if the sequence is compatible with the OMC21 standard, and then extracts its values. The sketch for OMC21 is thus prearranged to continuously monitor the transmission of the command bytes on the three communication ports: USB, serial and I²C. The port on which the data will arrive is unimportant, and at most they could even arrive at the same time, though if would be quite useless to do it; the advantage is anyway that of loading a single sketch, thus avoiding to go nuts because of programming. Once programmed, our OMC21 controller is ready to activate the motors, depending on the commands received: let’s see how to do it by means of some examples, by taking advantage of the various communication ports.
