ADcmXL3021_data_acquisition_issue

Background:

Raspberry Pi 2B to get the vibration data in ADcmXL3021 sensor via SPI, in RTS mode.

ADcmXL3021 datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADcmXL3021.pdf

Issue：

When I send the command to the sensor, most data are 0s, as the data format should be

And the data I get as below:

As I show above, the data I get should have 200 bytes, include the header 0xAD00, -x -y -z Vibration data and Temperature data, CRC bits. But now seems like almost all 0s.

Hardware connection:

ADcmXL3021 is powered by individual power supply(3.3V，30.6mA)

CS set as low, SYNC/RTS set as high(RTS need this pin high to keep conversion active).

Use python spidev for SPI communication, code as below:

=======================================================

# -*- coding:utf-8 -*-

#for ADcmXL3021 Sensor data acquistion

import time

from spidev import SpiDev

spi=SpiDev()  #build a slave

spi.open(0,0)  #Raspberry Pi SPICE0 Pin(the other is SPICE1), this is for CS

spi.mode=0b11  #RTS mode (SPI mode3)

spi.max_speed_hz=7800000  #for Raspberry Pi is 7.8,15.6MHz, but for ADc should be 12.5~14MHz, so I set as 7.8M, as a little slower should be ok

spi.lsbfirst = False   #msb,high bits first

spi.cshigh=False  #cs set as low

spi.bits_per_word=8   #Raspberry only support 8 bits, even ADc output data is 16 bits, I think just need to combine 2 received data

spi.writebytes([0xBE,0x08,0x00])  #send command to get the data

time.sleep(0.012)  #12ms delay between command and data receiving

data=spi.readbytes(200)  #read data in RTS mode,and then conbine 2 data into 1(here I not give out the code as I think it's easy to do)

print(data)

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Here, why I send the command is form the info in datasheet:

1011 1110 0000 1000 0000 0000:0XBE 0x08 0x00

From my side, maybe it’s caused by the commands format I send to the sensor is wrong.

also, different from other register map, the map of ADcmXL3021, has 7 pages, not sure how to send the command to tell the sensor which page I select, as I think before write and read to the register, need to give the register is in which page.

Hope you can share your point, many thanks.