Now let's get the Feather setup with CircuitPython, the necessary libraries, and the hourglass code.

## Prepare the Feather Sense

Follow this guide for setting up CircuitPython on the Feather nRF52840 Sense:

## Install Libraries

Follow this guide for installing libraries:

This guide has specifics on the libraries used with the LED matrices:

Make sure these libraries are in your CIRCUITPY/lib folder:

## Hourglass Code

And here is the hourglass code. If you haven't already, also make sure to have matrixsand.py copied to your CIRCUITPY folder. If you worked through the examples in the previous section, then that should already have been done.

Then save the code below as code.py and the hourglass should start.

```# SPDX-FileCopyrightText: 2020 Carter Nelson for Adafruit Industries
#

import time
import board
import matrixsand

DELAY = 0.05 # overall update rate

# the accelo

# the matrices
m1 = matrix.Matrix8x8(board.I2C(), 0x70)
m2 = matrix.Matrix8x8(board.I2C(), 0x71)

# the sand
sand1 = matrixsand.MatrixSand(8, 8)
sand2 = matrixsand.MatrixSand(8, 8)

# simple helper
def update_matrix(m, s):
for x in range(8):
for y in range(8):
m[x,y] = s[x,y]

# fill up some sand
for sx in range(8):
for sy in range(8):
sand1[sx, sy] = True
sand1[0,0] = sand1[0,1] = sand1[1,0] = False
sand1[0,2] = sand1[1,1] = sand1[2,0] = False

update_matrix(m1, sand1)
update_matrix(m2, sand2)

updated1 = updated2 = False

while True:
ax, ay, az = accelo.acceleration
# rotate coords
xx = -ax - ay
yy = -ax + ay
zz = az

# move grain of sand from upper to lower?
if yy > 0 and sand1[7,7] and not sand2[0,0] and not updated2:
sand1[7,7] = False
sand2[0,0] = True
updated1 = updated2 = True
# move grain of sand from lower to upper?
elif yy <= 0 and sand2[0,0] and not sand1[7,7] and not updated1:
sand2[0,0] = False
sand1[7,7] = True
updated1 = updated2 = True
# nope, just a regular update
else:
updated1 = sand1.iterate((xx, yy, zz))
updated2 = sand2.iterate((xx, yy, zz))

# update matrices if needed
if updated1:
update_matrix(m1, sand1)
if updated2:
update_matrix(m2, sand2)

time.sleep(DELAY)
```

This guide was first published on Jun 06, 2020. It was last updated on Jun 06, 2020.