the ADXL 345 accelerometer seems common enough, plenty of threads on this forum here, but a search of "GY-291" turns up only one thread in Spanish.
on the internet "GY-291" results in accelerometer modules (i think they're all from China) and i see they all use the ADXL 345 chip.
am wondering if anybody knows what the difference is; is the GY-291 code just to indicate the modules that are coming out of China, they all seem to be in blue.
the price difference is quite marked too - there doesn't seem to be much difference in the specs,
Chipset: ADXL345; Power supply :3~5V; Communication methods: the IIC/SPI communication protocol; Measuring range: +/- 2g +/-16g; 3-Axis, +/- 2g; +/-4g; +/-8g; +/- 16g
and this from SparkFun; ADXL-345 = $27.95
2.0-3.6VDC Supply Voltage
Ultra Low Power: 40uA in measurement mode, 0.1uA in standby@ 2.5V
Tap/Double Tap Detection
Free-Fall Detection
SPI and I2C interfaces
would those extra Detection features be one reason for the price difference ?
the more expensive board has LESS components on it... :-/
hi !
thanks for your response !!
wow, so they seem to be exactly the same, i guess there must be more demand for this chip which is pushing the price lower.
Those on Ebay cost between 2 and 3 dollars and use the same ADXL345 chip.
They have a voltage regulator so they can be use with 5V and they have pull-up resistors for the I2C bus.
The site dx.com has the same as those on Ebay, same quality, same sensor.
Companies like Adafruit and Sparkfun use better components, and they give all the information you need, schematics and code.
yeah, i guess "information has value in itself".
and User Manuals don't normally "fall off the back of a truck"
you could get a super cheap component or chip but it'd be of no use if you didn't know what to do with it (or use it properly), one could spend a lot of time (=money!) figuring out where an error is if they didn't have reliable information about it.
Well, I do buy modules from Ebay.
Sometimes a fake Arduino clone board has problems with a crystal or capacitor, because the cheapest components on the clones.
The RTC (Real Time Clock) on Ebay are know to cause a lot of trouble.
if you're knowledgable enough, buying cheap shouldn't be too risky 'coz you'd know how to troubleshoot.
it's the beginners that could get into trouble if they stinge on a cuppla bucks but then end up with a lot of frustration.
then again, if it's a hobby, it'll be a valuable learning experience... like myself and that ENC28J60 !!
Also, I suspect I might have to remove the I2C resistors if I have other sensor(s) on the bus that also have resistors included (a surface-mount desoldering job), if the total parallel resistances combined to a too-small value.