Does anyone used the micromega um-FPU v3.1 or 64 (http://micromegacorp.com/products.html
), if yes how fast do you get the results form it to arduino (i want to use I2C)?
I'm thinking to use it because it has fast 12bit ADC and also to make floating point calculations (for gps, motors and others)
but i'm afraid that the time gained in the calculations or analog reads will be lost in the communication time with the 328 chip.
Well the V3.1 datasheet gives performance speeds for all the instructions starting on pdf page 31. What I don't recall seeing is timing performance of the standard arduino software floating point functions and without that it's hard to estimate the improvement possible. Maybe the datasheet gives some comparisons? :http://micromegacorp.com/downloads/documentation/uMFPU-V3_1%20Datasheet.pdf
Note the chip also supports SPI communications with an arduino as well as serial and I2C and would be the fastest method I believe. The also have an arduino library to support usage of the chip. If you do get one be sure to let us know how it works out for you.