The Nemo Wide 2 uses the same communication protocol as the Icon HD,
except for two differences:
The Nemo Wide 2 requires a different baudrate and parity setting.
Unfortunately it doesn't seem possible to autodetect the correct
protocol variant at runtime. Attempting to proceed with incorrect
settings will render the device unresponsive and requires a battery
reset to recover.Therefore the model code needs to be provided as an
extra parameter, when opening the connection.
The Nemo Wide 2 also appears to have trouble downloading the entire
memory with a single request. Therefore the single large request is
split into many smaller ones. The offical Mares application uses 256
byte packets, and so do we. The Icon HD keeps using the large packets
because they are significant faster.
The extra model parameter breaks backwards compatibility!
The Petrel is slightly different from the Predator because the device
reorders the internal ringbuffer before sending the data. The most
recent dive is always the first one, and there is no need to search for
it, like we have to do for the Predator.
The exact OSTC variant can be detected by means of the serial number.
Each of the three variants is now assigned an artifical model number,
and included explicitly in the list of supported models.
Applications can now enumerate all the supported devices at runtime,
and don't have to maintain their own list anymore. The internal list
does include only those devices that have been confirmed to work at
least once without any major problems.
As the name already indicates, a device descriptor is lightweight
object which describes a single device. Currently, the api supports
getting the device name (vendor and product) and model number. But
this can extended with other features when necessary.
