Originally Posted By: Bluedeath
I ordered some A1302 from EBAY it turned out that they were china manufactured clones (i checked from the markings and thay are similar to allegro by spec sheet) ,but they work really well the only strange thing is that i can't get full travel in other words by using a 12 bit A/D i only get around 690 to 3700 (wich is anyhow fairly good by being more than 3000 discrete positions) instead of ideal 0 to 4096, the sensor is placed right in the middle of the "BIC assembly" and i used 5x5x5 neodimium magnets I tested by spinning the magnet assembly freely 360 several times and i never exceed thoose values. I laso tried to increase flux by adding magnets but the result not change. Im already satisfied with this setup but i was wondering if this is normal.

Clones that perform to a certain spec are pretty common with electronic components.

By the sounds of it, your setup has less sensitivity than it needs to 'saturate' the sensor. If you have calibrated it so that the stick can reach 0 and 100% in games (really important!), and you're happy with the center position then you're all good - 3000 steps is plenty. The 1302 has a sensitivity of 1.3mV/G, compared to 2.5 for the 1301 - so if you did want to increase it, you have the option to, if 1301s are available. The linearity of the setup is purely set by the angle range that the stick moves through. Much more than 45 degrees (total) and you'll start to see variable sensitivity.

According to the spec sheet, the 1301/2 (like the 1321) output can be between 0.2 and 4.7V - which means you can't get the A/D converter to read less than 160 or more than 3850, even when you have plenty of magnetic flux. This just needs to be calibrated out in the operating system, unless you want to use a signal amplifier to get a true 0 to 5 V output.