GPIO server

Via the GPIO server all IOs of Netzer can be addressed.

If the GPIO is activated, Netzer opens a TCP port (factory setting 65000) after restart. Activation and the port can be carried out by general settings via the website (see figure). The settings do not become directly effective, but only after restart!

For simple tests of the server and the protocol every terminal program may be used that is capable of building up connections via Raw TCP sockets, such as e.g. the Windows HyperTerminal. Upon successful connection establishment, authentification takes place if activated. Otherwise, the protocol phase is directly entered into.

For the GPIO server, authentification can be activated on the GPIO settings website.

For authentification, the user accounts of the access control are used. The rights of the individual user accounts are replicated as well. The guest login for example can only access to GPIO values in reading.

After connection establishment, the input prompt for the user name is displayed:

login:

After that, the password:

password:

In the event of an incorrect entry the connection is interrupted by the GPIO server. If everything is okay, the protocol phase is entered into.

In the GPIO server, a simple protocol is implemented.

Thanks to this protocol, digital inputs and outputs as well as ADC and PWM/pulse outputs can be read. Only digital outputs as well as PWM/pulse outputs can be written. Furthermore, these outputs must not be occupied by functions of the serial server.

Reading or writing is done by commands. Invididual commands are separated from each other by Whitespaces (space characters, tab, word wrap etc. - all characters with the ASCII code ⇐ 32).

Each pin can be unambiguously addressed via its ID. Here an overview of all IDs:

Reading of pins works as follows:

a=? Server reply: a=1
e=? Server reply: e=03ff
m=? Server reply: m=0
x=? Server reply: x=0011

Depending on whether the pin is configured digital or as ADC/PWM, the GPIO servier supplies binary or numerical values. The radix of numerical values can be changed between hexadecimal and decimal using the GPIO setting on the GPIO configuration page.

The wildcard ID x always supplies the digital state of all pins, regardless of whether a pin supplies binary or numerical values. At bit level, the states of the individual pins as per the following table are possible:

Writing on pins is done analogously:

a=1 Server reply: a=1
d=0123 Server reply: d=0123
m=0 Server reply: m=0
x=0123 Server reply: x=0123

The wildcard ID x describes only the pins configured as digital outputs and not occupied by the serial server.

For every digital input, an event trigger may be activated on the GPIO configuration page.

Thus, the GPIO sever independently sends protocol messages in the event of an accordingly configured amendment.