I’ve been trying to use a Raspberry Pi 3 B+ to get data from an accelerometer, namely ADXL 357 , via I2C but the problem is that the data rate is about 200 Hz or even less. I tried to set the accelerometer to high speed mode and it didn’t help. I also tried to change the baudrate in the rasberry but i wouldn’t go higher than 2.000.000 or something similar.

import smbus
import time
import csv
import RPi.GPIO as GPIO
from datetime import datetime



i2c_ch=1

i2c_adress = 0x1D

acc_range = 0x81 # 0x01->8g, 0x02->20g, 0x03->40g

# i'm putting 0x81 rather than 0x01 to set it to high speed mode rather than fast mode

bus = smbus.SMBus(i2c_ch)



#val = bus.read_i2c_block_data(i2c_adress,reg_range,3)
def configure_raspberry():
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(8,GPIO.IN,pull_up_down=GPIO.PUD_DOWN)
    GPIO.setup(18,GPIO.OUT)

def configure_adxl() :

    #reset
    bus.write_byte_data(i2c_adress,0x2f,0x52)

    #set filter

    bus.write_byte_data(i2c_adress,0x28,0x01)

    # set i2c speed to normal and acceleration range
    bus.write_byte_data(i2c_adress,0x2c,acc_range)

    #set in measurement mode (not standby)
    bus.write_byte_data(i2c_adress,0x2d,0x00)

def get_temperature() :

    temp1 = bus.read_byte_data(i2c_adress,0x06)
    temp2 = bus.read_byte_data(i2c_adress,0x07)
    temp = (temp1 << 8) | temp2
    temp = (float)(1852 - temp)/9.05 + 25
    return temp

def get_x_accel() :
    x1 = bus.read_byte_data(i2c_adress,0x08)
    x2 = bus.read_byte_data(i2c_adress,0x09)
    x3 = bus.read_byte_data(i2c_adress,0x0A)
    x = (x1 << 12) | (x2 << 4) | (x3 >> 4)
    if(x & 0x80000) :
        x = (x & 0x7ffff) - 0x80000
    return x

def get_y_accel() :
    y1 = bus.read_byte_data(i2c_adress,0x0B)
    y2 = bus.read_byte_data(i2c_adress,0x0C)
    y3 = bus.read_byte_data(i2c_adress,0x0D)
    y = (y1 << 12) | (y2 << 4) | (y3 >> 4)
    if(y & 0x80000) :
        y = (y & 0x7ffff) - 0x80000
    return y

def get_z_accel() :
    z1 = bus.read_byte_data(i2c_adress,0x0E)
    z2 = bus.read_byte_data(i2c_adress,0x0F)
    z3 = bus.read_byte_data(i2c_adress,0x8)
    z = (z1 << 12) | (z2 << 4) | (z3 >> 4)
    if(z & 0x80000) :
        z = (z & 0x7ffff) - 0x80000
    return z

def convert_in_g(accel) :
    if(acc_range == 0x01) :
        accel = (float)(accel)/0x7ffff*8
    if(acc_range == 0x02) :
        accel = (float)(accel)/0x7ffff*20
    if(acc_range == 0x03) :
        accel = (float)(accel)/0x7ffff*40
    return accel



configure_adxl()
configure_raspberry()

while True :
        date = datetime.now()

        timestamp = datetime.timestamp(date)
        dateStr = date.strftime("%d-%b-%Y (%H:%M:%S.%f)")

        name = dateStr +'.csv'


        if GPIO.input(8) == GPIO.HIGH :
            f = open(name,'a',newline = "")
            c = csv.writer(f)

            time.sleep(0.08)
            while GPIO.input(8) == GPIO.HIGH :
                GPIO.output(18,GPIO.HIGH)
                temp = get_temperature()
                print("temperature uncalibrated : ",temp)
                print("_________________________________________________________")
                print("\n")
                x = get_x_accel()
                print("x raw acceleration : ",x)
                x = convert_in_g(x)
                print("x acceleration in g : ",x)
                print("\n")
                y = get_y_accel()
                print("y raw acceleration : ",y)
                y = convert_in_g(y)
                print("y acceleration in g : ",y)
                print("\n")
                z = get_z_accel()
                print("z raw acceleration : ",z)
                z = convert_in_g(z)
                print("z acceleration in g : ",z)
                print("\n\n\n\n")
                date2 = datetime.now()

                timestamp = datetime.timestamp(date2)
                c.writerow([timestamp,x,y,z])
            f.close()
            GPIO.output(18,GPIO.LOW)