Has anyone looked at the Kionix KXM52-1050 tri-axial accelerometer as a replacement for the ADXL accelerometers? I would like to use it in a PIC project I am designing, but I have no clue as to how to go about interfacing the critter. There is an app note on how to use the sensor to correct a digital magnetic compass for tilt. The data sheets and app notes can be found at:
I could use some help here.
Any enlightenment will be appreciated.
TIA
Vic Fraenckel
Didn’t even know they existed. If they’re cheaper than Analog parts, it might be interesting, but I like how Analog puts out a reference signal and you can change the response range by varying a few external passives. Anyway…
You’ve got 3 analog lines coming off that sensor, for your X, Y, and Z axis. There are no “center” signals for comparison, so you have to depend on your calibration. They provide two digital inputs, the PS pin for shutting down the unit and the TEST pin that shoves all accelerometer readings up 1G for calibration. Obviously, you only REALLY need the three analog lines.
Now, your measurement range is 0.33V to 2.97V. Not too shabby, you probably won’t need to level shift (it is a 3.3V part after all). I’d have to check the PIC datasheet to see what the recommended analog Z is, but I think it’s 2.5Kohm max, so you might need to throw in an op-amp voltage follower circuit for each analog line. If you don’t, the ADC might read low to not being able to gather enough charge for an accurate reading.
Hmmm… I see the sensor will work at up to 5V. Appears that the unit is ratiometric, so… scribble scribble scribble at 5V you’re looking at a center of 2.75V, 1V/G, so your range then would be 0.75V to 4.75V. This is actually a bit of an advantage, as you don’t have to worry about varying power supply levels (battery) affecting the reading 
So, summary, I’d personally run each of the three analog lines into a voltage follower circuit then to the PIC’s ADC. If it’s a low power design, hook up the PS and the TEST digital lines, otherwise, TEST alone should be sufficient to calibrate the unit. A callibration routine of placing it on a level surface may be recommended, too
Vic:
How did you find these parts? What’s the ballpark price?
Digikey sells ST’s tri axis for about $20. 44 pin, 7 x 7 mm, 100 k Ohms output impedence, so it’s not as cool as this part.
I called Kionix a couple times. They never called me back 
Let me know if any info surfaces. We are banking on the Analog ADXL330 in July of '06
-Nathan
John,
How did you find these parts? What’s the ballpark price?
I’m not sure how I stumbled upon Kionix. I believe I was doing a google for accelerometers and the name popped up. Their web site gets you to their dealers and I queried the one near me and the response (not very professional, I must admit) was $8 US eash for small quantitys
Holy Moly. I’ll get right on it Monday. $8 seems too good to be true. Maybe they thought you were asking for a two axis?
Freescale has a new 3-axis accelerometer, the MMA7260. They are about $6 (1000). I’ve ordered a sample.
Leon
I work for Kionix if there is anything i can help you with, just let me know
Hi Shawshank,
I called Kionix a few months ago (April I think) looking for info and pricing for your tri-ax sensors. I left two messages with no returned calls. No info on the site. No distributors. Pretty tough for us small guys.
We’ve since gone with the Motorola part that just came out : http://www.sparkfun.com/shop/index.php? … itemid=439
Feel free to have a Kionix rep call us if they’d like.
-Nathan
Hmmmm - anybody looked at the KXP74 series from Kionix (http://www.kionix.com/Product%20Sheets/ … Series.pdf) three axis, and best of all, SPI! Being that my current project uses SPI to interface to essentially every single component - this seems pretty ideal! It’s in some awful .5mm pitch package though - I’m unsure if the pads are even exposed. (I’ve soldered .5mm pitch before - and while I didn’t enjoy it one bit it was doable)
Does anybody know of any other 3 axis accelerometer chips? I was really interested in the Freescale MMA7260Q so I ordered up a sample, then tonight I got a message saying it was backordered till the 22nd… of SEPTEMBER!!!
Argh.
Wow… I just got a response from Kionix today. They sell KXP74s for $21.50 - which is alot, but oh well. But what really bothers me is that they have “a domestic shipping and handling charge of $35.00.”
I don’t think I’ll be doing business with them.
edit: update: I e-mailed them and voiced my displeasure with this shipping fee - and they agreed to completely waive the fee and instead of shipping via the standard fed ex overnight, to ship via USPS, at no cost to me. So I’ll soon have a couple KXP74s to play with!