k-space/micropython-skeleton
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19
Makefile Normal file
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# Makefile for the board
NAME=esp32-20180222-v1.9.3-347-g6e675c1b.bin
all: flash console
flash:
esptool.py -p /dev/ttyUSB0 -b 921600 erase_flash
esptool.py -p /dev/ttyUSB0 -b 921600 write_flash --flash_mode dio 0x1000 bin/${NAME}
sleep 5
ampy -p /dev/ttyUSB0 put ssd1306.py
console:
echo "Ctrl-A + Ctrl-Q to close Picocom"
picocom -b115200 /dev/ttyUSB0
dep:
sudo apt install python3-pip
sudo pip3 install adafruit-ampy

192
README.md
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# micropython-skeleton
# Hello MicroPython
## Getting started
MicroPython project skeleton
```
git clone http://git.k-space.ee/lauri/micropython-skeleton
cd micropython-skeleton
make
```
First let's some LED-s blinking.
Press Ctrl-E for paste mode, otherwise spaces get mangled.
Press Ctrl-Shift-V for pasting.
Press Ctrl-D to exit paste mode and evaluate the code.
```
from time import sleep
from machine import Pin
# RGB LED is connected to programmable pins 12, 13, 15
led_red = Pin(12, Pin.OUT)
led_green = Pin(13, Pin.OUT)
led_blue = Pin(15, Pin.OUT)
# The values are inverted because 3.3v is common pin
led_red.value(1)
led_green.value(1)
led_blue.value(1)
for j in range(0, 5):
led_red.value(0)
sleep(1)
led_red.value(1)
led_green.value(0)
sleep(1)
led_green.value(1)
led_blue.value(0)
sleep(1)
led_blue.value(1)
```
Tasks:
1. Modify the code so yellow, cyan, magenda and white would be included.
# Button presses
On the board there is button labelled "Boot", this is hooked up to pin 2.
By default there is a resistor which pulls the voltage on the pin to 3.3v, but when button is pressed the pin is shorted to ground so the voltage goes to 0v.
Most modern solutions use interrupts to detect voltage change on the pin:
```
from machine import Pin
from time import sleep
Pin(12, Pin.OUT).value(1)
Pin(13, Pin.OUT).value(1)
led_blue = Pin(15, Pin.OUT)
button = Pin(0)
turned_off = False
def callback(p):
global turned_off
turned_off = not turned_off
led_blue.value(turned_off)
# Execute function 'callback' when voltage goes from 3.3v to 0v on pin 0
button.irq(trigger=Pin.IRQ_FALLING, handler=callback)
```
Tasks:
1. Modify the code so pressing button shuffles between off, red, green, blue, yellow, cyan, magenta and white
# Driving OLED screens
Let's get some pixels on the screen.
There's 128x64 pixels monochrome OLED screen connected via I2C bus on the pins 4 and 5.
```
from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
i2c = I2C(-1, Pin(4),Pin(5), freq=400000) # Bitbanged I2C bus
oled = SSD1306_I2C(128, 64, i2c)
oled.invert(0) # White text on black background
oled.contrast(255) # Maximum contrast
oled.fill(0)
name = "Lauri"
oled.text("Hi %s" % name, 10, 10)
oled.show()
```
Tasks:
1. When button is pressed show a corresponding message on the screen - lights turned on/off or the name of the color shown
## Temperature & humidity
Next let's hook up DHT11 sensor to the board and measure the temperature.
```
from time import sleep
from machine import Pin
from dht import DHT11
d = DHT11(Pin(4))
try:
d.measure()
except OSError:
print("Sensor not connected")
else:
print("Temperature %sC" % d.temperature())
print("Humidity %s%%" % d.humidity())
finally:
sleep(1)
```
Tasks:
1. Get temperature and humidity displayed on the screen
## Connecting to internet
Exit the serial console by pressing Ctrl-A and then Ctrl-Q.
Upload module to handle WebSockets and return to Python prompt:
```
ampy -p /dev/ttyUSB0 put uwebsockets.py
ampy -p /dev/ttyUSB0 put boot.py # Script that connects to itcollege network
make console
```
Press EN button on the board to reset the board.
Paste following:
```
import sys
import uwebsockets
from machine import Pin
Pin(12, Pin.OUT).value(1)
Pin(13, Pin.OUT).value(1)
led_blue = Pin(15, Pin.OUT)
channel = "living-room-of-lauri"
uri = "ws://iot.koodur.com:80/ws/" + channel
print("Connecting to:", uri)
conn = uwebsockets.connect(uri)
conn.send("alive")
turned_off = False
while True:
print("Reading message...")
fin, opcode, data = conn.read_frame()
if data == "toggle":
turned_off = not turned_off
led_blue.value(turned_off)
else:
print("Got unknown command:", data)
```
Using web browser navigate [here](http://iot.koodur.com/demo2.html#living-room-of-lauri)
1. Move to another channel to prevent flipping lights in my living room
2. Improve the code so the "Boot" button and button in the web interface both work simultaneously
3. Download the HTML file and add buttons to select different colors, adjust Python code to handle new commands
# Summary
ESP32 microcontroller with MicroPython is a really cheap way to get started with the IoT stuff. See more detailed information [here](https://lauri.xn--vsandi-pxa.com/2017/06/espressif.html).
Some more tricks to try:
* Add dimming of LED-s with PWM
* Add [colorpicker](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/color)
Other interesting projects with ESP8266 and ESP32 microcontrollers:
* [Nixie clock](https://github.com/k-space-ee/nixiesp12) with ESP8266
* [Sumorobot](http://robot.itcollege.ee/sumorobot/2017/08/25/sumesp-prototype/) with ESP32

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bin/esp32-20180222-v1.9.3-347-g6e675c1b.bin Normal file
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boot.py Normal file
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# Connect to wireless network as client
import network
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("itcollege")

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main.py Normal file
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from time import sleep_ms
from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
i2c = I2C(-1, Pin(4),Pin(5),freq=400000) # Bitbanged I2C bus
assert 60 in i2c.scan(), "No OLED display detected!"
oled = SSD1306_I2C(128, 64, i2c)
buf = "wubba lubba dub dub "
oled.invert(0) # White text on black background
oled.contrast(255) # Maximum contrast
j = 0
while True:
oled.fill(0)
oled.text(buf[j%len(buf):]+buf, 10, 10)
oled.show()
sleep_ms(20)
j += 1

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ssd1306.py Normal file
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# MicroPython SSD1306 OLED driver, I2C and SPI interfaces
from micropython import const
import framebuf
# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xa4)
SET_NORM_INV = const(0xa6)
SET_DISP = const(0xae)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xa0)
SET_MUX_RATIO = const(0xa8)
SET_COM_OUT_DIR = const(0xc0)
SET_DISP_OFFSET = const(0xd3)
SET_COM_PIN_CFG = const(0xda)
SET_DISP_CLK_DIV = const(0xd5)
SET_PRECHARGE = const(0xd9)
SET_VCOM_DESEL = const(0xdb)
SET_CHARGE_PUMP = const(0x8d)
# Subclassing FrameBuffer provides support for graphics primitives
# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
class SSD1306(framebuf.FrameBuffer):
def __init__(self, width, height, external_vcc):
self.width = width
self.height = height
self.external_vcc = external_vcc
self.pages = self.height // 8
self.buffer = bytearray(self.pages * self.width)
super().__init__(self.buffer, self.width, self.height, framebuf.MONO_VLSB)
self.init_display()
def init_display(self):
for cmd in (
SET_DISP | 0x00, # off
# address setting
SET_MEM_ADDR, 0x00, # horizontal
# resolution and layout
SET_DISP_START_LINE | 0x00,
SET_SEG_REMAP | 0x01, # column addr 127 mapped to SEG0
SET_MUX_RATIO, self.height - 1,
SET_COM_OUT_DIR | 0x08, # scan from COM[N] to COM0
SET_DISP_OFFSET, 0x00,
SET_COM_PIN_CFG, 0x02 if self.height == 32 else 0x12,
# timing and driving scheme
SET_DISP_CLK_DIV, 0x80,
SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,
SET_VCOM_DESEL, 0x30, # 0.83*Vcc
# display
SET_CONTRAST, 0xff, # maximum
SET_ENTIRE_ON, # output follows RAM contents
SET_NORM_INV, # not inverted
# charge pump
SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
SET_DISP | 0x01): # on
self.write_cmd(cmd)
self.fill(0)
self.show()
def poweroff(self):
self.write_cmd(SET_DISP | 0x00)
def poweron(self):
self.write_cmd(SET_DISP | 0x01)
def contrast(self, contrast):
self.write_cmd(SET_CONTRAST)
self.write_cmd(contrast)
def invert(self, invert):
self.write_cmd(SET_NORM_INV | (invert & 1))
def show(self):
x0 = 0
x1 = self.width - 1
if self.width == 64:
# displays with width of 64 pixels are shifted by 32
x0 += 32
x1 += 32
self.write_cmd(SET_COL_ADDR)
self.write_cmd(x0)
self.write_cmd(x1)
self.write_cmd(SET_PAGE_ADDR)
self.write_cmd(0)
self.write_cmd(self.pages - 1)
self.write_data(self.buffer)
class SSD1306_I2C(SSD1306):
def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False):
self.i2c = i2c
self.addr = addr
self.temp = bytearray(2)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.temp[0] = 0x80 # Co=1, D/C#=0
self.temp[1] = cmd
self.i2c.writeto(self.addr, self.temp)
def write_data(self, buf):
self.temp[0] = self.addr << 1
self.temp[1] = 0x40 # Co=0, D/C#=1
self.i2c.start()
self.i2c.write(self.temp)
self.i2c.write(buf)
self.i2c.stop()
class SSD1306_SPI(SSD1306):
def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
self.rate = 10 * 1024 * 1024
dc.init(dc.OUT, value=0)
res.init(res.OUT, value=0)
cs.init(cs.OUT, value=1)
self.spi = spi
self.dc = dc
self.res = res
self.cs = cs
import time
self.res(1)
time.sleep_ms(1)
self.res(0)
time.sleep_ms(10)
self.res(1)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs(1)
self.dc(0)
self.cs(0)
self.spi.write(bytearray([cmd]))
self.cs(1)
def write_data(self, buf):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs(1)
self.dc(1)
self.cs(0)
self.spi.write(buf)
self.cs(1)

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"""
Websockets client for micropython
Based very heavily on
https://github.com/aaugustin/websockets/blob/master/websockets/client.py
"""
import ubinascii as binascii
import urandom as random
import ure as re
import ustruct as struct
import usocket as socket
from ucollections import namedtuple
# Opcodes
OP_CONT = const(0x0)
OP_TEXT = const(0x1)
OP_BYTES = const(0x2)
OP_CLOSE = const(0x8)
OP_PING = const(0x9)
OP_PONG = const(0xa)
# Close codes
CLOSE_OK = const(1000)
CLOSE_GOING_AWAY = const(1001)
CLOSE_PROTOCOL_ERROR = const(1002)
CLOSE_DATA_NOT_SUPPORTED = const(1003)
CLOSE_BAD_DATA = const(1007)
CLOSE_POLICY_VIOLATION = const(1008)
CLOSE_TOO_BIG = const(1009)
CLOSE_MISSING_EXTN = const(1010)
CLOSE_BAD_CONDITION = const(1011)
URL_RE = re.compile(r'ws://([A-Za-z0-9\-\.]+)(?:\:([0-9]+))?(/.+)?')
URI = namedtuple('URI', ('hostname', 'port', 'path'))
def urlparse(uri):
match = URL_RE.match(uri)
if match:
return URI(match.group(1), int(match.group(2)), match.group(3))
else:
raise ValueError("Invalid URL: %s" % uri)
class Websocket:
is_client = False
def __init__(self, sock):
self._sock = sock
self.open = True
def __enter__(self):
return self
def __exit__(self, exc_type, exc, tb):
self.close()
def settimeout(self, timeout):
self._sock.settimeout(timeout)
def read_frame(self, max_size=None):
# Frame header
byte1, byte2 = struct.unpack('!BB', self._sock.read(2))
# Byte 1: FIN(1) _(1) _(1) _(1) OPCODE(4)
fin = bool(byte1 & 0x80)
opcode = byte1 & 0x0f
# Byte 2: MASK(1) LENGTH(7)
mask = bool(byte2 & (1 << 7))
length = byte2 & 0x7f
if length == 126: # Magic number, length header is 2 bytes
length, = struct.unpack('!H', self._sock.read(2))
elif length == 127: # Magic number, length header is 8 bytes
length, = struct.unpack('!Q', self._sock.read(8))
if mask: # Mask is 4 bytes
mask_bits = self._sock.read(4)
try:
data = self._sock.read(length)
except MemoryError:
# We can't receive this many bytes, close the socket
self.close(code=CLOSE_TOO_BIG)
return True, OP_CLOSE, None
if mask:
data = bytes(b ^ mask_bits[i % 4]
for i, b in enumerate(data))
return fin, opcode, data.decode("utf-8")
def write_frame(self, opcode, data=b''):
fin = True
mask = self.is_client # messages sent by client are masked
length = len(data)
# Frame header
# Byte 1: FIN(1) _(1) _(1) _(1) OPCODE(4)
byte1 = 0x80 if fin else 0
byte1 |= opcode
# Byte 2: MASK(1) LENGTH(7)
byte2 = 0x80 if mask else 0
if length < 126: # 126 is magic value to use 2-byte length header
byte2 |= length
self._sock.write(struct.pack('!BB', byte1, byte2))
elif length < (1 << 16): # Length fits in 2-bytes
byte2 |= 126 # Magic code
self._sock.write(struct.pack('!BBH', byte1, byte2, length))
elif length < (1 << 64):
byte2 |= 127 # Magic code
self._sock.write(struct.pack('!BBQ', byte1, byte2, length))
else:
raise ValueError()
if mask: # Mask is 4 bytes
mask_bits = struct.pack('!I', random.getrandbits(32))
self._sock.write(mask_bits)
data = bytes(b ^ mask_bits[i % 4]
for i, b in enumerate(data))
self._sock.write(data)
def recv(self):
assert self.open
while self.open:
try:
fin, opcode, data = self.read_frame()
except ValueError:
self._close()
return
if not fin:
raise NotImplementedError()
if opcode == OP_TEXT:
return data.decode('utf-8')
elif opcode == OP_BYTES:
return data
elif opcode == OP_CLOSE:
self._close()
return
elif opcode == OP_PONG:
# Ignore this frame, keep waiting for a data frame
continue
elif opcode == OP_PING:
# We need to send a pong frame
self.write_frame(OP_PONG, data)
# And then wait to receive
continue
elif opcode == OP_CONT:
# This is a continuation of a previous frame
raise NotImplementedError(opcode)
else:
raise ValueError(opcode)
def send(self, buf):
assert self.open
if isinstance(buf, str):
opcode = OP_TEXT
buf = buf.encode('utf-8')
elif isinstance(buf, bytes):
opcode = OP_BYTES
else:
raise TypeError()
self.write_frame(opcode, buf)
def close(self, code=CLOSE_OK, reason=''):
if not self.open:
return
buf = struct.pack('!H', code) + reason.encode('utf-8')
self.write_frame(OP_CLOSE, buf)
self._close()
def _close(self):
self.open = False
self._sock.close()
class WebsocketClient(Websocket):
is_client = True
def connect(uri):
"""
Connect a websocket.
"""
uri = urlparse(uri)
assert uri
sock = socket.socket()
addr = socket.getaddrinfo(uri.hostname, uri.port)
sock.connect(addr[0][4])
def send_header(header, *args):
sock.send(header % args + '\r\n')
# Sec-WebSocket-Key is 16 bytes of random base64 encoded
key = binascii.b2a_base64(bytes(random.getrandbits(8)
for _ in range(16)))[:-1]
send_header(b'GET %s HTTP/1.1', uri.path or '/')
send_header(b'Host: %s:%s', uri.hostname, uri.port)
send_header(b'Connection: Upgrade')
send_header(b'Upgrade: websocket')
send_header(b'Sec-WebSocket-Key: %s', key)
send_header(b'Sec-WebSocket-Version: 13')
send_header(b'Origin: http://localhost')
send_header(b'')
header = sock.readline()[:-2]
assert header == b'HTTP/1.1 101 Switching Protocols', header
# We don't (currently) need these headers
# FIXME: should we check the return key?
while header:
header = sock.readline()[:-2]
return WebsocketClient(sock)