Using the Impinj Web interface


When you boot up the Impinj reader, it runs a web server with web status and configuration pages, as well as a simple query interface. By default it comes up as a DHCP client, so you can find it by just typing speedway into your browser's address bar. If you are having trouble resolving the hostname, you can get the IP number by hooking up a serial cable to the Impinj reader, setting your terminal program for 115200/8/n/1/None, and resetting the reader. When the reader finishes booting it will report its IP number, which you can then use it in the browser address bar. If the reader has already booted, enter "show network summary" at the command line.

When you go to the reader page, you'll be presented with a login. By default the username is root and the password is impinj. to run the query interface, your browser will need to support Java. Sometimes we've had problems with one browser or another not working with the Impinj web server; If IE won't work, switch to FF, and vice versa.

To run the query interface, go to the RFIDemo tab. The first page is Settings. On this page, set Mode to Dense Reader M=4, and enable on my antennas you actually have attached to your reader. Search Mode should be set to 0. (Note: these instructions are for Impinj version 3.0.2, but these should also work for version 2.6 readers as well.)

Now go to the Operation page, and select start. If you have WISPs near the antenna, they should start showing up on the page. If you don't, sanity check your reader setup with an off-the-shelf gen2 tag.

Warning: sometimes when running long tests, the reader reports that there are no tags present. When you probe the WISP, you see that the reader isn't putting out any power, even though the web app appears to be running fine. The fix is to reload the web page. And if you are testing WISP code and hit what you think is a lockup, always verifiy it with a non-WISP tag. It might be the reader's problem.

Issuing gen2 read commands


Important: In both 2.6 and 3.0 version of the reader firmware, the Impinj web interface appears to cache gen2 read data. (The increasing tag count report is somewhat misleading, as it just indicates follow up query/acks commands, not the entire query/ack/request rn/read sequence.) This makes it unsuitable for varying data (e.g., sensor data). If you're trying to process varying data via the read command, look at the UsingImpinjSDK page instead. It will do what you want.

Assuming you already have your Settings page configured, go to the Tag Access page. Go to the Halt filter section and under operation select A only. Under membank pick EPC and under comparison go to not equals. Leave the patterns section as 0000. In the action section, under operation select read, and under membank pick user. Check the box marked 0 to indicate the length of the read. (Note: the length field is in 16 bit words, not bytes.) Now go to the operations page and start it.

This forces the reader to stop for every tag with an EPC not equal to zero (in other words, all tags) and read the first 16 bits out of the user membank. (Well, not really. See the note about caching at the beginning of this section.) If you're using hw40_D51.c with the enable reads #define set to 1, you should be seeing 0304 as the data returned.