Simple RFID reading circuit, and simple RFID code?

The AS IC has some cool features but we haven't found time to test it yet.

The predecessor of the TRF7970 was well suited for boosting the power level to 1W and reading at up to 40cm - again, we haven't had the time to test whether this still works.

The MLX works at more that 100 tags / s and at over 25cm read range for an A4-size antenna under good conditions if designed well (unboosted!).

Thank you all for the replies. I think the example project is a great place to start with RFID.

As for my application, I wanted the tag and readers to fit into a very small place which still having a read distance of 1-3 meters.

Thoughts?

Cabe

@Cabe: now you start adding requirements

Well, let me put it this way: If you are expecting to read at 1-3 meters distance then you will definitely need UHF Readers / Tags - 125kHz and 13.56MHz just don't reach that far.

The need for UHF will lead to either a drastic increase in your design project complexity - you definitely need very solid HF design know-how to produce good results - or we come back to my suggestion from ealier about using a module. In your case you will even need at least a mid-range module. Again, I can only speak for metraTec but we have a mid-range module which is (if I correctly recall) 40 x 42mm in size - would you consider this to be "very small"? With the module you will need an antenna for which different sizes are available - maybe this can alleviate the size issues somewhat by placing the reader somewhere else nearby and only needing to fit the antenna in your "small space".

Tag design at UHF frequencies is also not trivial - there aren't many people who do this themselves with good results - please let me know if you want professional help with this.

There is also a solution on 13,56MHz but it is a little bit "cheating".

You could reach 1 meter with 1 reader with boosted signal output and 1 very good designed antenne.
When you build a array of  3 antennes you get 3 times 1 meter thus 3 meters

Problems that occure : You need to use a antenne multiplexer between the antenne input of the module and the 3 antennas
                                  The detection goes 3 times slower. (a little bit more actualy)
                                  Possible interference between the antennas (should not be a problem because only 1 antenna is active at each time)

Its al about how many you want to spend on your design, a UHF system that has a super range of 1 to 100m and even more for 3 meter is a little bit pricy for its purpose.

There is also a solution on 13,56MHz but it is a little bit "cheating".

You could reach 1 meter with 1 reader with boosted signal output and 1 very good designed antenne.
When you build a array of  3 antennes you get 3 times 1 meter thus 3 meters

Problems that occure : You need to use a antenne multiplexer between the antenne input of the module and the 3 antennas
                                  The detection goes 3 times slower. (a little bit more actualy)
                                  Possible interference between the antennas (should not be a problem because only 1 antenna is active at each time)

Its al about how many you want to spend on your design, a UHF system that has a super range of 1 to 100m and even more for 3 meter is a little bit pricy for its purpose.

The few HF readers that I know that can read at 1m (I would say that there are 5 different ones worldwide that can do this) use Helmholtz antenna configurations with a diameter of around 70cm (this is physically limited), hand-picked large tags and readers the size of shoe boxes. Price for such readers is definitely above 1k€, the antennas are hundreds of €, you need a splitter for each Helmholtz setup and a multiplexer (each costing hundreds of €) and using three antennas (or three Helmholtz settings) is not always feasible as this places antennas in the middle of the 3m reading range. As I said, HF is not a good choice and I would not consider this to be "very small" - plus it needs at least 20W of power.

A complete mid-range UHF reader can be had at 500€, the antenna might come at 200€ and you are finished with a completely packaged system at prices for 1pc. If you are planning on doing your own PCB things get quite a bit cheaper - antennas as low as 35€, the mid-range reader module at e.g. at 265€ - again prices for 1pc. - as you know these decrease significantly with quantity.