Coink

https://www.hackster.io

Necesitaremos …

Micropython

NodeMCU

I2C

Cableado

Código

from machine import I2C
from machine import Pin


i2c = I2C(scl=Pin(5), sda=Pin(4), freq=400000)
devices = i2c.scan()

address = devices[0]
i2c.writeto(address, b'123')          # Write 3 bytes
i2c.readfrom(address, 4)              # Read 4 bytes
i2c.readfrom_mem(address, 8, 3)       # Read 3 bytes at address 8
i2c.writeto_mem(address, 2, b'\x10')  # Write 1 byte at address 2

Hojas de especificaciones

Código final

def read_registers(i2c):

    read_address = 0x6b
    trigger = 1 << 7
    request = bytearray([read_address, trigger])
    reply = bytearray(7)

    i2c.start()
    ack = i2c.write(request)
    i2c.readinto(reply)
    i2c.stop()

    return reply, ack

WiFi y HTTP 😍

station = WLAN(STA_IF)
station.active(True)
station.connect(config['ssid'], config['password'])

reply = urequests.get(url)
reply = urequests.post(url, data=bytearray(ring))

Captura de datos del sensor

• tiempo total 1 segundo de datos
• 1000 lecturas por segundo
• sensor 3D con dimensiones x, y, z y tiempo

Manejo eficiente de memoria -> buffers + ‘array’

x_array = array.array('h', (0 for i in range(num_measures)))

https://docs.micropython.org/array

Memoria vs tiempo de ejecución

def read_coin(self):
        '''
        Read magnetic sensor values and save on RAM (arrays)
        '''
def save_readings(self):
        '''
        Save magnetic sensor values from RAM to a file
        '''

Buffer circular, la solución definitiva

ring = array.array('h', (0 for i in range(4 * num_measures)))

def loop(self):
        ....
        position = i * 4
        ring[position] = time.ticks_us() % 65536
        ring[position + 1] = x
        ring[position + 2] = y
        ring[position + 3] = z
        .....
        urequests.post(url, data=bytearray(ring))

Analizando monedas

Características

Diferenciación (min)

Diferenciación (d0)

Diferenciación (l0)

La nube con Flask ☁️

ThingSpeak

[data, time] = thingSpeakRead(516536, 'Fields', [1], 'NumDays', 7);
data = timetable(time, data)
data = retime(data, 'daily', 'sum')
bar(data.time, data.Variables, 'FaceColor', [1 .5 0])

Fuentes

• Código: github.com/CojoCompany/coink
• Documentación: coink.readthedocs.io
• Presentación: cojocompany.github.io/PythonVigo-2019-Coink/

¿Preguntas? 😊