MMA7455L Accelerometer Mode control question

[jason540]

MMA7455L datasheet said that when the accelerometer in standby Mode (Address $16 8'bxxxxxx00) it can read and write to the registers with the I2C/SPI available,but can not measurement a now data?

i have a other question about a g-cell select, if i select 2g to drive a MMA7455L what is the output value?(is it 00H ~ 40H) or in datacheet table 7 Acceleration vs output trun 90oC = -1g($C1)??

i can not fully to understand this accelerometer

 

[DirtyLude]

Your English is difficult to understand, but yes, when it's in standby mode you can read the registers, but the measurement data wont be updated.

You get the full range of the output for whatever g level you select, so for the 8bit output register you will get -127 thru +127. Otherwise the g-select wouldn't make any sense. Figure 17 and table 13 in the datasheet are correct.

 

[jason540]

What is the different between 10-bits and 8-bits data output value,10-bits data output are more sensitivity than 8-bits data output? Is it only 8g is selectable with 10-bits data at Measurement Mode?

If I measurement the data first I should turn to standby Mode to set up the drive, second I turn to measurement mode to enable all three axes, take a new data in register $00 to &08, than I should turn to standby Mode again to transmit to MCU(I use PIC 18F4620), it is correct?

 

[DirtyLude]

10 bit reading has a higher resolution and is only used in 8g reading.

You can read/write in any mode. If all you want to do is measure data, put it in the measurement mode and leave it there. If you want to save power and you aren't using it put it in standby mode.

If all you want to do is read the measurements, set the mode register: measurement and g-level, then read the output value registers.

 

[jason540]

Thank you so much

 

[jason540]

Thank you so much