AT+i Programmer's Manual - SE Spezial-Electronic AG

26.7 Host Interaction Mode
iChip Embedded Web Server
Host Interaction mode allows OEMs to design and implement a product-related
embedded website that is managed by iChip on behalf of the host. The host-defined
embedded website supports live host parameter monitoring and updating by a remote
browser. This is achieved by a dynamic AT+i layer implemented across the serial link
between the host and iChip.
The application developer creates a website using conventional web authoring tools. The
HTML or WAP files can then be edited to contain Parameter Tags. Parameter tags are
regarded as placeholders in HTML or WAP files. They are replaced on-the-fly with realtime
values as the page is served to the browser. Browsers may also change values of
Parameter Tags in order to submit the value back to the host via iChip. This is done by
defining the Parameter Tag in the NAME field in an HTML FORM (without the (~)
characters). The iChip WPWD parameter is used to password-protect remote Parameter
Tags update. See Security and Restrictions.
Once a website is created and Parameter Tags are edited in, the site is packed and
uploaded to iChip. The website is linked into the iChip firmware, automatically
expanding the existing AT+i command set to encompass the website Parameter Tags.
This happens when the web server is activated using the +iWWW command.
Extended AT+i commands have the following syntax:
> AT+i=
> AT+i?
for setting and querying Parameter Tag values, respectively.
For example, the ~temperature~ Parameter Tag referenced in a web page, can be set
using:
> AT+itemperature=’45 Deg.’
and queried using:
> AT+itemperature?
When the host issues a Set Parameter Tag Value command, iChip links the updated value
to the Parameter Tag and stores it in its internal RAM. In response to a browser‘s GET
request, the real value is substituted everywhere in the page where the Parameter Tag
exists while the page is being served, on-the-fly.
Parameter Tag values are printable ASCII text. This convention allows implementing any
part of an HTML or WAP page as a parameter tag: numeric values, links, file names,
HTML code, etc. A Parameter Tag value is limited to 256 characters.
Parameter Tag values can be changed and submitted from the browser end using HTML
forms. iChip stores the updated values and responds appropriately to host AT+i parameter
query commands. Thus, the host can poll specific parameters for value changes. Status
Report 7 (AT+iRP7) can be used to facilitate polling on all application web parameters.
RP7 returns a bitmap result, where bit 10 is set to ‗1‘ if one or more application web
parameters have been remotely changed. The iChip DTRH signal is an associated
hardware signal that can be used to generate an interrupt on the host CPU when new data