Error relating to ADXL355 accelerometer library in micropyhon.

[jwpark98]

I am new to micropython. Due to this forum, I have achieved several success. Thank you all for this help. However, I recently suffered from dealing with the accelerometer, adxl355. As a mechanical engineer, I am very interested in measuring acceleration of an object. To do, I have tested several sensors such as adxl345, mpu6050, and adxl355. I completed adxl345 and mpu6050, but adxl355 is not easy due to its complexity. Below is my adxl355.py (mycropython api version) referred from adxl355.py (python version) and adxl345.py (micropython version). Especially, the code treating byte operator is not easy to me. I do not know how to deal with byte sections. Could you please let me know any good adxl355.py (micropython) or teach me how to modify this code. I could not find any reliable code for adxl355 in micropython.

---------- code ------------

Import necessary libraries

from micropython import const
from machine import SPI, Pin
import time

ADXL355 addresses

DEVID_AD = const(0x00)
DEVID_MST = const(0x01)
PARTID = const(0x02)
REVID = const(0x03)
STATUS = const(0x04)
FIFO_ENTRIES = const(0x05)
TEMP2 = const(0x06)
TEMP1 = const(0x07)

XDATA3 = const(0x08)
XDATA2 = const(0x09)
XDATA1 = const(0x0A)
YDATA3 = const(0x0B)
YDATA2 = const(0x0C)
YDATA1 = const(0x0D)
ZDATA3 = const(0x0E)
ZDATA2 = const(0x0F)
ZDATA1 = const(0x10)

FIFO_DATA = const(0x11)
OFFSET_X_H = const(0x1E)
OFFSET_X_L = const(0x1F)
OFFSET_Y_H = const(0x20)
OFFSET_Y_L = const(0x21)
OFFSET_Z_H = const(0x22)
OFFSET_Z_L = const(0x23)
ACT_EN = const(0x24)
ACT_THRESH_H = const(0x25)
ACT_THRESH_L = const(0x26)
ACT_COUNT = const(0x27)
FILTER = const(0x28)
FIFO_SAMPLES = const(0x29)
INT_MAP = const(0x2A)
SYNC = const(0x2B)
RANGE = const(0x2C)
POWER_CTL = const(0x2D)
SELF_TEST = const(0x2E)
RESET = const(0x2F)

Data ranges

RANGE_2G = const(0x01)
RANGE_4G = const(0x02)
RANGE_8G = const(0x03)

Values

READ_BIT = 0x01
WRITE_BIT = 0x00
DUMMY_BYTE = 0xAA

class ADXL355:
def init(self, spi_id, cs_pin=5, scl_pin=18, sda_pin=23, sdo_pin=19, spi_freq=10000000):
#SPI0, id=0 / SPI1(HSPI), id=1 / SPI2(VSPI), id=2

SPI pins

  self.spi = SPI(spi_id, sck=Pin(scl_pin, Pin.OUT), mosi=Pin(sda_pin, Pin.OUT), miso=Pin(sdo_pin), baudrate=spi_freq, polarity=1, phase=1, bits=8, firstbit=SPI.MSB)
  time.sleep(0.2)
  self.cs = Pin(cs_pin, Pin.OUT, value=1)
  time.sleep(0.2)

def del(self):
self.spi.deinit()

== writing ==

def write_data(self, regaddr:int, the_byte:int):
self.cs.value(0)
self.spi.write(bytearray((regaddr, the_byte)))
self.cs.value(1)
return self

== readings ==

def read_data(self, regaddr: int, nbytes: int) -> bytearray or int:
self.cs.value(0)
value = self.spi.read(nbytes + 1, regaddr)[1:]
self.cs.value(1)
return value

#buf = bytearray(4)
def read_into(self, buf: bytearray, regaddr: int) -> bytearray:
self.cs.value(0)
self.spi.readinto(buf, regaddr)
self.cs.value(1)
return buf

def read_multiple_data(self, address_list):
spi_ops = []
for address in address_list:
spi_ops.append(address << 1 | READ_BIT)
spi_ops.append(DUMMY_BYTE)

  return self.spi.read(spi_ops)[1:]

def get_temperature(self):
# Reading data
temp_data = [self.spi.read(TEMP1, 4), self.spi.read(TEMP2, 4)]
# Join data
temp_data = (temp_data[0]) + ((temp_data[1] - ((temp_data[1] >> 4) << 4)) << 8)
# temp_data = (1852 - temp_data) / 9.05 + 19.21
return temp_data

def get_acceleration(self):
## reading data
xData = [self.read_data(XDATA1, 4), self.read_data(XDATA2, 4), self.read_data(XDATA3, 4)]
yData = [self.read_data(YDATA1, 4), self.read_data(YDATA2, 4), self.read_data(YDATA3, 4)]
zData = [self.read_data(ZDATA1, 4), self.read_data(ZDATA2, 4), self.read_data(ZDATA3, 4)]

  # Join data
  x_data = (xData[0] >> 4) + (xData[1] << 4) + (xData[2] << 12)
  y_data = (yData[0] >> 4) + (yData[1] << 4) + (yData[2] << 12)
  z_data = (zData[0] >> 4) + (zData[1] << 4) + (zData[2] << 12)

  # Apply two complement
  if x_data & 0x80000 == 0x80000:
     x_data = ~x_data + 1

  if y_data & 0x80000 == 0x80000:
     y_data = ~y_data + 1

  if z_data & 0x80000 == 0x80000:
     z_data = ~z_data + 1

  # Return values
  return [x_data, y_data, z_data]

def _reset_settings(self):
## reset all settings
self.write_data(RESET, 0x52)

== Get measuring range ==

def _set_measure_range(self, measure_range:int):
self.write_data(RANGE, measure_range)
return self

if name == 'main':
spi0 = ADXL355(spi_id=2, cs_pin=5, scl_pin=18, sda_pin=23, sdo_pin=19, spi_freq=10000000)

Set sensor

spi0._reset_settings()
spi0._set_measure_range(RANGE_2G)

f_s = 3 # Hz
dt = 1/f_s # sec.

axes = spi0.get_acceleration() # pylint: disable=invalid-name
print(axes)

---

When I run the code, following error is occurred.

typeerror: unsupported types for rshift: 'bytes', 'int'

I think the error is related to the part as below:

x_data = (xData[0] >> 4) + (xData[1] << 4) + (xData[2] << 12)

Maybe I did some mistake to port adxl355.py (python version) into micropython version.

This work is pretty important to me since I am studying some measurement system to obtain acceleration data on the surface of machinery. Since I am not expert in micropython programming, I do not know where I have to start to modify my ugly code.

JW

[robert-hh]

xData is a list of bytearray objects, so xData[0] is a bytearray object, not an int. You may have intended e.g. xData[0][0] etc., which is an int, or convert the content of what has been returned by read_data89 to an int first and add that to the list.

[jwpark98]

Thanks for this quick reply. The function ‘read_data’ returns byte. Python code uses << or >> operator to get values however there is no example to treat them in micropython. Could you please show me how to get values as in same manner?

[jwpark98]

Do you mean that I needed to cast the returned type of read_data() as below?
FROM
x_data = (xData[0] >> 4) + (xData[1] << 4) + (xData[2] << 12)
TO
x_data = (int(xData[0]) >> 4) + (int(xData[1]) << 4) + (int(xData[2]) << 12)

[jwpark98]

This also returned error messege.

• ValueError: invalid syntax for integer with base 10

[jwpark98]

When I print xData using self.read_Data(xData, it gave me [b’\xff\xff\xff\xff’, b’\xff\xff\xff\xff, b’\xff\xff\xff\xff]. I think it is something wrong.

[robert-hh]

The function read_data() returns a bytearray of five bytes, as your print shows, not a single integer. That why you get the coding error. And it returns five bytes because your code requests five bytes. You can convert that into an integer using e.g. struct.unpack().
The fact that this bytearray is all 0xff is a different problem. It seems that you do not get any data from the sensor. So check the wiring and the way you intialize the sensor.

[brokenbrigde9000]

@jwpark98 Did you manage to get the ADXL355 running with micropython?