Overview

Keep up to date on the current value of Bitcoin or your total wallet value with the PyPortal Bitcoin Display!

The simple version of this project will display the current value of Bitcoin in one of three currencies -- USD, Euros, or GBP. The slightly more complex version uses a text transform to present the total value of your Bitcoin wallet based upon the current Bitcoin value.

All made in CircuitPython running on the PyPortal accessing the Coindesk API wirelessly!

Parts

All of the parts needed are included in AdaBox 011 which is carried in the shop now. Or the parts can be purchased separately.

AdaBox011 - PyPortal

PRODUCT ID: 4061
Reach out beyond your desk - to the stars and beyond - with PyPortal! This ADABOX features a new, easy-to-use IoT device that allows you to customize and create your...
OUT OF STOCK

Separate parts

Adafruit PyPortal - CircuitPython Powered Internet Display

PRODUCT ID: 4116
PyPortal, our easy-to-use IoT device that allows you to create all the things for the “Internet of Things” in minutes. Make custom touch screen interface...
OUT OF STOCK

Adafruit PyPortal Desktop Stand Enclosure Kit

PRODUCT ID: 4146
PyPortal is our easy-to-use IoT device that allows you to create all the things for the “Internet of Things” in minutes. Create little pocket...
$9.95
IN STOCK

USB cable - USB A to Micro-B

PRODUCT ID: 592
This here is your standard A to micro-B USB cable, for USB 1.1 or 2.0. Perfect for connecting a PC to your Metro, Feather, Raspberry Pi or other dev-board or...
$2.95
IN STOCK

Install CircuitPython

CircuitPython is a derivative of MicroPython designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the CIRCUITPY "flash" drive to iterate.

The following instructions will show you how to install CircuitPython. If you've already installed CircuitPython but are looking to update it or reinstall it, the same steps work for that as well!

Set up CircuitPython Quick Start!

Follow this quick step-by-step for super-fast Python power :)

Click the link above to download the latest version of CircuitPython for the PyPortal.

Download and save it to your desktop (or wherever is handy).

Plug your PyPortal into your computer using a known-good USB cable.

A lot of people end up using charge-only USB cables and it is very frustrating! So make sure you have a USB cable you know is good for data sync.

Double-click the Reset button on the top in the middle (magenta arrow) on your board, and you will see the NeoPixel RGB LED (green arrow) turn green. If it turns red, check the USB cable, try another USB port, etc. Note: The little red LED next to the USB connector will pulse red. That's ok!

If double-clicking doesn't work the first time, try again. Sometimes it can take a few tries to get the rhythm right!

You will see a new disk drive appear called PORTALBOOT.

Drag the adafruit-circuitpython-pyportal-<whatever>.uf2 file to PORTALBOOT.

The LED will flash. Then, the PORTALBOOT drive will disappear and a new disk drive called CIRCUITPY will appear.

If you haven't added any code to your board, the only file that will be present is boot_out.txt. This is absolutely normal! It's time for you to add your code.py and get started!

That's it, you're done! :)

PyPortal Default Files

Click below to download a zip of the files that shipped on the PyPortal.

PyPortal CircuitPython Setup

To use all the amazing features of your PyPortal with CircuitPython, you must first install a number of libraries. This page covers that process.

Adafruit CircuitPython Bundle

Download the Adafruit CircuitPython Library Bundle. You can find the latest release here:

Download the adafruit-circuitpython-bundle-4.x-mpy-*.zip bundle zip file, and unzip a folder of the same name. Inside you'll find a lib folder. You have two options:

  • You can add the lib folder to your CIRCUITPY drive. This will ensure you have all the drivers. But it will take a bunch of space on the 8 MB disk
  • Add each library as you need it, this will reduce the space usage but you'll need to put in a little more effort.

At a minimum we recommend the following libraries, in fact we more than recommend. They're basically required. So grab them and install them into CIRCUITPY/lib now!

  • adafruit_esp32spi - This is the library that gives you internet access via the ESP32 using (you guessed it!) SPI transport. You need this for anything Internet
  • adafruit_requests - This library allows us to perform HTTP requests and get responses back from servers. GET/POST/PUT/PATCH - they're all in here!
  • adafruit_pyportal - This is our friendly wrapper library that does a lot of our projects, displays graphics and text, fetches data from the internet. Nearly all of our projects depend on it!
  • adafruit_touchscreen - a library for reading touches from the resistive touchscreen. Handles all the analog noodling, rotation and calibration for you.
  • adafruit_cursorcontrol - a library for reading PyGamer and PyBadge joystick and buttons. Handles all the graphics, button press reading and joystick movement for you.
  • adafruit_io - this library helps connect the PyPortal to our free datalogging and viewing service
  • adafruit_imageload - an image display helper, required for any graphics!
  • adafruit_display_text - not surprisingly, it displays text on the screen
  • adafruit_bitmap_font - we have fancy font support, and its easy to make new fonts. This library reads and parses font files.
  • adafruit_slideshow - for making image slideshows - handy for quick display of graphics and sound
  • neopixel - for controlling the onboard neopixel
  • adafruit_adt7410 - library to read the temperature from the on-board Analog Devices ADT7410 precision temperature sensor
  • adafruit_sdcard - support for reading/writing data from the onboard SD card slot.
  • adafruit_bus_device - low level support for I2C/SPI

Internet Connect!

Once you have CircuitPython setup and libraries installed we can get your board connected to the Internet. Note that access to enterprise level secured WiFi networks is not currently supported, only WiFi networks that require SSID and password.

To get connected, you will need to start by creating a secrets file.

What's a secrets file?

We expect people to share tons of projects as they build CircuitPython WiFi widgets. What we want to avoid is people accidentally sharing their passwords or secret tokens and API keys. So, we designed all our examples to use a secrets.py file, that is in your CIRCUITPY drive, to hold secret/private/custom data. That way you can share your main project without worrying about accidentally sharing private stuff.

Your secrets.py file should look like this:

Download: file
# This file is where you keep secret settings, passwords, and tokens!
# If you put them in the code you risk committing that info or sharing it

secrets = {
    'ssid' : 'home ssid',
    'password' : 'my password',
    'timezone' : "America/New_York", # http://worldtimeapi.org/timezones
    'github_token' : 'fawfj23rakjnfawiefa',
    'hackaday_token' : 'h4xx0rs3kret',
    }

Inside is a python dictionary named secrets with a line for each entry. Each entry has an entry name (say 'ssid') and then a colon to separate it from the entry key 'home ssid' and finally a comma ,

At a minimum you'll need the ssid and password for your local WiFi setup. As you make projects you may need more tokens and keys, just add them one line at a time. See for example other tokens such as one for accessing github or the hackaday API. Other non-secret data like your timezone can also go here, just cause its called secrets doesn't mean you can't have general customization data in there!

For the correct time zone string, look at http://worldtimeapi.org/timezones and remember that if your city is not listed, look for a city in the same time zone, for example Boston, New York, Philadelphia, Washington DC, and Miami are all on the same time as New York.

Of course, don't share your secrets.py - keep that out of GitHub, Discord or other project-sharing sites.

Connect to WiFi

OK now you have your secrets setup - you can connect to the Internet. Lets use the ESP32SPI and the Requests libraries - you'll need to visit the CircuitPython bundle and install:

  • adafruit_bus_device
  • adafruit_esp32spi
  • adafruit_requests
  • neopixel

Into your lib folder. Once that's done, load up the following example using Mu or your favorite editor:

import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

print("ESP32 SPI webclient test")

TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_URL = "http://api.coindesk.com/v1/bpi/currentprice/USD.json"


# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

requests.set_socket(socket, esp)

if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
    print("ESP32 found and in idle mode")
print("Firmware vers.", esp.firmware_version)
print("MAC addr:", [hex(i) for i in esp.MAC_address])

for ap in esp.scan_networks():
    print("\t%s\t\tRSSI: %d" % (str(ap['ssid'], 'utf-8'), ap['rssi']))

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
    except RuntimeError as e:
        print("could not connect to AP, retrying: ",e)
        continue
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)
print("My IP address is", esp.pretty_ip(esp.ip_address))
print("IP lookup adafruit.com: %s" % esp.pretty_ip(esp.get_host_by_name("adafruit.com")))
print("Ping google.com: %d ms" % esp.ping("google.com"))

#esp._debug = True
print("Fetching text from", TEXT_URL)
r = requests.get(TEXT_URL)
print('-'*40)
print(r.text)
print('-'*40)
r.close()

print()
print("Fetching json from", JSON_URL)
r = requests.get(JSON_URL)
print('-'*40)
print(r.json())
print('-'*40)
r.close()

print("Done!")

And save it to your board, with the name code.py

This first connection example doesn't use a secrets file - you'll hand-enter your SSID/password to verify connectivity first!

Then go down to this line

esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')

and change MY_SSID_NAME and MY_SSID_PASSWORD to your access point name and password, keeping them within the '' quotes. (This example doesn't use the secrets' file, but its also very stand-alone so if other things seem to not work you can always re-load this. You should get something like the following:

In order, the example code...

Initializes the ESP32 over SPI using the SPI port and 3 control pins:

Download: file
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

Tells our requests library the type of socket we're using (socket type varies by connectivity type - we'll be using the adafruit_esp32spi_socket for this example). We'll also set the interface to an esp object. This is a little bit of a hack, but it lets us use requests like CPython does.

Download: file
requests.set_socket(socket, esp)

Verifies an ESP32 is found, checks the firmware and MAC address

Download: file
if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
    print("ESP32 found and in idle mode")
print("Firmware vers.", esp.firmware_version)
print("MAC addr:", [hex(i) for i in esp.MAC_address])

Performs a scan of all access points it can see and prints out the name and signal strength:

Download: file
for ap in esp.scan_networks():
    print("\t%s\t\tRSSI: %d" % (str(ap['ssid'], 'utf-8'), ap['rssi']))

Connects to the AP we've defined here, then prints out the local IP address, attempts to do a domain name lookup and ping google.com to check network connectivity (note sometimes the ping fails or takes a while, this isn't a big deal)

Download: file
    print("Connecting to AP...")
esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)
print("My IP address is", esp.pretty_ip(esp.ip_address))
print("IP lookup adafruit.com: %s" % esp.pretty_ip(esp.get_host_by_name("adafruit.com")))
print("Ping google.com: %d ms" % esp.ping("google.com"))
  

OK now we're getting to the really interesting part. With a SAMD51 or other large-RAM (well, over 32 KB) device, we can do a lot of neat tricks. Like for example we can implement an interface a lot like requests - which makes getting data really really easy

To read in all the text from a web URL call requests.get - you can pass in https URLs for SSL connectivity

Download: file
TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
print("Fetching text from", TEXT_URL)
r = requests.get(TEXT_URL)
print('-'*40)
print(r.text)
print('-'*40)
r.close()

Or, if the data is in structured JSON, you can get the json pre-parsed into a Python dictionary that can be easily queried or traversed. (Again, only for nRF52840, M4 and other high-RAM boards)

Download: file
JSON_URL = "http://api.coindesk.com/v1/bpi/currentprice/USD.json"
print("Fetching json from", JSON_URL)
r = requests.get(JSON_URL)
print('-'*40)
print(r.json())
print('-'*40)
r.close()

Requests

We've written a requests-like library for web interfacing named Adafruit_CircuitPython_Requests. This library allows you to send HTTP/1.1 requests without "crafting" them and provides helpful methods for parsing the response from the server.

# adafruit_requests usage with an esp32spi_socket
import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
    except RuntimeError as e:
        print("could not connect to AP, retrying: ",e)
        continue
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
requests.set_socket(socket, esp)

TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_GET_URL = "http://httpbin.org/get"
JSON_POST_URL = "http://httpbin.org/post"

print("Fetching text from %s"%TEXT_URL)
response = requests.get(TEXT_URL)
print('-'*40)

print("Text Response: ", response.text)
print('-'*40)
response.close()

print("Fetching JSON data from %s"%JSON_GET_URL)
response = requests.get(JSON_GET_URL)
print('-'*40)

print("JSON Response: ", response.json())
print('-'*40)
response.close()

data = '31F'
print("POSTing data to {0}: {1}".format(JSON_POST_URL, data))
response = requests.post(JSON_POST_URL, data=data)
print('-'*40)

json_resp = response.json()
# Parse out the 'data' key from json_resp dict.
print("Data received from server:", json_resp['data'])
print('-'*40)
response.close()

json_data = {"Date" : "July 25, 2019"}
print("POSTing data to {0}: {1}".format(JSON_POST_URL, json_data))
response = requests.post(JSON_POST_URL, json=json_data)
print('-'*40)

json_resp = response.json()
# Parse out the 'json' key from json_resp dict.
print("JSON Data received from server:", json_resp['json'])
print('-'*40)
response.close()

The code first sets up the ESP32SPI interface. Then, it initializes a request object using an ESP32 socket and the esp object.

Download: file
import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
    except RuntimeError as e:
        print("could not connect to AP, retrying: ",e)
        continue
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
requests.set_socket(socket, esp)

HTTP GET with Requests

The code makes a HTTP GET request to Adafruit's WiFi testing website - http://wifitest.adafruit.com/testwifi/index.html.

To do this, we'll pass the URL into requests.get(). We're also going to save the response from the server into a variable named response.

While we requested data from the server, we'd what the server responded with. Since we already saved the server's response, we can read it back. Luckily for us, requests automatically decodes the server's response into human-readable text, you can read it back by calling response.text.

Lastly, we'll perform a bit of cleanup by calling response.close(). This closes, deletes, and collect's the response's data. 

Download: file
print("Fetching text from %s"%TEXT_URL)
response = requests.get(TEXT_URL)
print('-'*40)

print("Text Response: ", response.text)
print('-'*40)
response.close()

While some servers respond with text, some respond with json-formatted data consisting of attribute–value pairs.

CircuitPython_Requests can convert a JSON-formatted response from a server into a CPython dict. object.

We can also fetch and parse json data. We'll send a HTTP get to a url we know returns a json-formatted response (instead of text data). 

Then, the code calls response.json() to convert the response to a CPython dict

Download: file
print("Fetching JSON data from %s"%JSON_GET_URL)
response = requests.get(JSON_GET_URL)
print('-'*40)

print("JSON Response: ", response.json())
print('-'*40)
response.close()

HTTP POST with Requests

Requests can also POST data to a server by calling the requests.post method, passing it a data value.

Download: file
data = '31F'
print("POSTing data to {0}: {1}".format(JSON_POST_URL, data))
response = requests.post(JSON_POST_URL, data=data)
print('-'*40)

json_resp = response.json()
# Parse out the 'data' key from json_resp dict.
print("Data received from server:", json_resp['data'])
print('-'*40)
response.close()

You can also post json-formatted data to a server by passing json_data into the requests.post method.

Download: file
    json_data = {"Date" : "July 25, 2019"}
print("POSTing data to {0}: {1}".format(JSON_POST_URL, json_data))
response = requests.post(JSON_POST_URL, json=json_data)
print('-'*40)

json_resp = response.json()
# Parse out the 'json' key from json_resp dict.
print("JSON Data received from server:", json_resp['json'])
print('-'*40)
response.close()
  

Advanced Requests Usage

Want to send custom HTTP headers, parse the response as raw bytes, or handle a response's http status code in your CircuitPython code?

We've written an example to show advanced usage of the requests module below.

import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
    except RuntimeError as e:
        print("could not connect to AP, retrying: ",e)
        continue
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
requests.set_socket(socket, esp)

JSON_GET_URL = "http://httpbin.org/get"

# Define a custom header as a dict.
headers = {"user-agent" : "blinka/1.0.0"}

print("Fetching JSON data from %s..."%JSON_GET_URL)
response = requests.get(JSON_GET_URL, headers=headers)
print('-'*60)

json_data = response.json()
headers = json_data['headers']
print("Response's Custom User-Agent Header: {0}".format(headers['User-Agent']))
print('-'*60)

# Read Response's HTTP status code
print("Response HTTP Status Code: ", response.status_code)
print('-'*60)

# Read Response, as raw bytes instead of pretty text
print("Raw Response: ", response.content)

# Close, delete and collect the response data
response.close()

WiFi Manager

That simpletest example works but its a little finicky - you need to constantly check WiFi status and have many loops to manage connections and disconnections. For more advanced uses, we recommend using the WiFiManager object. It will wrap the connection/status/requests loop for you - reconnecting if WiFi drops, resetting the ESP32 if it gets into a bad state, etc.

Here's a more advanced example that shows the WiFi manager and also how to POST data with some extra headers:

import time
import board
import busio
from digitalio import DigitalInOut
import neopixel
from adafruit_esp32spi import adafruit_esp32spi
from adafruit_esp32spi import adafruit_esp32spi_wifimanager

print("ESP32 SPI webclient test")

# Get wifi details and more from a secrets.py file
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)
"""Use below for Most Boards"""
status_light = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=0.2) # Uncomment for Most Boards
"""Uncomment below for ItsyBitsy M4"""
# status_light = dotstar.DotStar(board.APA102_SCK, board.APA102_MOSI, 1, brightness=0.2)
# Uncomment below for an externally defined RGB LED
# import adafruit_rgbled
# from adafruit_esp32spi import PWMOut
# RED_LED = PWMOut.PWMOut(esp, 26)
# GREEN_LED = PWMOut.PWMOut(esp, 27)
# BLUE_LED = PWMOut.PWMOut(esp, 25)
# status_light = adafruit_rgbled.RGBLED(RED_LED, BLUE_LED, GREEN_LED)
wifi = adafruit_esp32spi_wifimanager.ESPSPI_WiFiManager(esp, secrets, status_light)

counter = 0

while True:
    try:
        print("Posting data...", end='')
        data = counter
        feed = 'test'
        payload = {'value':data}
        response = wifi.post(
            "https://io.adafruit.com/api/v2/"+secrets['aio_username']+"/feeds/"+feed+"/data",
            json=payload,
            headers={"X-AIO-KEY":secrets['aio_key']})
        print(response.json())
        response.close()
        counter = counter + 1
        print("OK")
    except (ValueError, RuntimeError) as e:
        print("Failed to get data, retrying\n", e)
        wifi.reset()
        continue
    response = None
    time.sleep(15)

You'll note here we use a secrets.py file to manage our SSID info. The wifimanager is given the ESP32 object, secrets and a neopixel for status indication.

Note, you'll need to add a some additional information to your secrets file so that the code can query the Adafruit IO API:

  • aio_username
  • aio_key

You can go to your adafruit.io View AIO Key link to get those two values and add them to the secrets file, which will now look something like this:

Download: file
# This file is where you keep secret settings, passwords, and tokens!
# If you put them in the code you risk committing that info or sharing it

secrets = {
    'ssid' : '_your_ssid_',
    'password' : '_your_wifi_password_',
    'timezone' : "America/Los_Angeles", # http://worldtimeapi.org/timezones
    'aio_username' : '_your_aio_username_',
    'aio_key' : '_your_aio_key_',
    }

Next, set up an Adafruit IO feed named test

We can then have a simple loop for posting data to Adafruit IO without having to deal with connecting or initializing the hardware!

Take a look at your test feed on Adafruit.io and you'll see the value increase each time the CircuitPython board posts data to it!

Bitcoin Value Display

Bitcoin Value

With the PyPortal running CircuitPython code, we can have the PyPortal display the current value of Bitcoin according to the coindesk.com API.

The PyPortal Bitcoin Display will do the following:

  • Display a custom background .bmp
  • Determine the current value of Bitcoin using the WiFi connection to the Internet
  • Display the current Bitcoin value converted into USD, Euros, or GBP.

Install CircuitPython Code and Assets

In the embedded code element below, click on the Download: Project Zip link, and save the .zip archive file to your computer.

Then, uncompress the .zip file, it will unpack to a folder named PyPortal_Bitcoin.

Copy the contents of the PyPortal_Bitcoin directory to your PyPortal's CIRCUITPY drive, and then be sure to rename the bitcoin.py file to code.py so it will automatically run when the PyPortal re-starts.

This is what the final contents of the CIRCUITPY drive will look like:

"""
This example will access the coindesk API, grab a number like bitcoin value in
USD and display it on a screen
If you can find something that spits out JSON data, we can display it!
"""
import time
import board
from adafruit_pyportal import PyPortal

# You can display in 'GBP', 'EUR' or 'USD'
CURRENCY = 'USD'
# Set up where we'll be fetching data from
DATA_SOURCE = "https://api.coindesk.com/v1/bpi/currentprice.json"
DATA_LOCATION = ['bpi', CURRENCY, 'rate_float']

def text_transform(val):
    if CURRENCY == 'USD':
        return "$%d" % val
    if CURRENCY == 'EUR':
        return "‎€%d" % val
    if CURRENCY == 'GBP':
        return "£%d" % val
    return "%d" % val

# the current working directory (where this file is)
cwd = ("/"+__file__).rsplit('/', 1)[0]
pyportal = PyPortal(url=DATA_SOURCE, json_path=DATA_LOCATION,
                    status_neopixel=board.NEOPIXEL,
                    default_bg=cwd+"/bitcoin_background.bmp",
                    text_font=cwd+"/fonts/Arial-Bold-24-Complete.bdf",
                    text_position=(195, 130),
                    text_color=0x0,
                    text_transform=text_transform)
pyportal.preload_font(b'$012345789')  # preload numbers
pyportal.preload_font((0x00A3, 0x20AC)) # preload gbp/euro symbol

while True:
    try:
        value = pyportal.fetch()
        print("Response is", value)
    except (ValueError, RuntimeError) as e:
        print("Some error occured, retrying! -", e)

    time.sleep(3*60)  # wait 3 minutes
If you run into any errors, such as "ImportError: no module named `adafruit_display_text.label`" be sure to update your libraries to the latest release bundle!

How it Works

The PyPortal Bitcoin Display is doing the following things;

Background

First, it displays a bitmap graphic named bitcoin_background.bmp as the screen's background. This is a 320 x 240 pixel RGB 16-bit raster graphic in .bmp format.

Font

To display information on the screen, the PyPortal code will use a  bitmapped font overlayed on top of the background. The font used here is are bitmap fonts made from the Arial typeface. You can learn more about converting type in this guide.

In order to speed up the display of text, the pyportal.preload_font() command is used to place the needed glyphs into memory.

JSON

So how does the PyPortal Bitcoin Display actually stay up to date with the current value of Bitcoin? By fetching the currentprice.json JSON file from the coindesk.com website's API!

Coindesk generates a JSON file with the current value of Bitcoin at the address https://api.coindesk.com/v1/bpi/currentprice.json

This file contains all sorts of information, delivered in an easy-to-parse format. If you visit that URL by copying the address and pasting it into the Load Url button of the online code "beautifier" https://codebeautify.org/jsonviewer you'll see the raw JSON file next to a nicely formatted version of it (choose "View" from the dropdown menu in the right hand box to change the display format).

Here it is in a raw-er form, but still using indentation and carriage returns to make it readable:

Download: file
{
  "time": {
    "updated": "Mar 26, 2019 14:55:00 UTC",
    "updatedISO": "2019-03-26T14:55:00+00:00",
    "updateduk": "Mar 26, 2019 at 14:55 GMT"
  },
  "disclaimer": "This data was produced from the CoinDesk Bitcoin Price Index (USD). Non-USD currency data converted using hourly conversion rate from openexchangerates.org",
  "chartName": "Bitcoin",
  "bpi": {
    "USD": {
      "code": "USD",
      "symbol": "$",
      "rate": "3,930.3000",
      "description": "United States Dollar",
      "rate_float": 3930.3
    },
    "GBP": {
      "code": "GBP",
      "symbol": "£",
      "rate": "2,972.8750",
      "description": "British Pound Sterling",
      "rate_float": 2972.875
    },
    "EUR": {
      "code": "EUR",
      "symbol": "€",
      "rate": "3,482.6035",
      "description": "Euro",
      "rate_float": 3482.6035
    }
  }
}

Keys

If we look a bit further down the JSON page, we'll see a key called bpi that has three sub-trees, USD, GBP, and EUR. Each of those, in turn, have their own sub-trees with five keys: code, symbol, rate, description, and rate_float

The raw JSON for one of the rate_float key : value pairs looks like this: "rate_float": 3930.3

Our CircuitPython code is able to grab and parse this data using these variables, where the CURRENCY value is used to choose from the three currency sub-trees:

Download: file
CURRENCY = 'USD'
DATA_SOURCE = "https://api.coindesk.com/v1/bpi/currentprice.json"
DATA_LOCATION = ['bpi', CURRENCY, 'rate_float']

Traversing JSON

The DATA_LOCATION contains three values that we use to traverse the JSON file. In the image above, note how there is a tree hierarchy indicated by the indentation level. The bpi(Bitcoin Price Index) key is at the top level of the file's hierarchy, so we can call its name first, followed by the CURRENCY key which is USD in this case (you can change to EUR or GBP if you like). Finally, we specify the rate_float key and get for the value of it, in this case 3930.3.

You can see this more clearly by switching to the "Form" view of the code beautifier.

Our DATA_LOCATION, therefore, is:

["bpi", "USD", "rate_float"]

PyPortal Constructor

When we set up the pyportal constructor, we are providing it with these things:

  • url to query
  • json_path to traverse and find the key:value pair we need
  • default_bg path and name to display the background bitmap
  • text_font path and name to the font used for displaying the follower count value
  • text_position on the screen's x/y coordinate system
  • text_color
  • text_transform this is used to format the text string, in this case by adding the currency symbol in front of the chosen currency for US dollars $ , Euros € , or GB pounds £.

Fetch

With the PyPortal set up, we can then use pyportal.fetch() to do the query and parsing of the data and then display it on screen on top of the background image.

This repeats every three minutes to stay current!

Customization

You can customize this project to make it your own and point to different website API's as the source of your JSON data, as well as adjust the graphics and text.

Text Position

Depending on the design of your background bitmap and the length of the text you're displaying, you may want to reposition the text and caption. You can do this with the text_position and caption_position options.

The PyPortal's display is 320 pixels wide and 240 pixels high. In order to refer to those positions on the screen, we use an x/y coordinate system, where x is horizontal and y is vertical.

The origin of this coordinate system is the upper left corner. This means that a pixel placed at the upper left corner would be (0,0) and the lower right corner would be (320, 240).

Text Color

Another way to customize your stats trophy is to adjust the color of the text. The line text_color=0xFFFFFF in the constructor shows how. You will need to use the hexidecimal value for any color you want to display.

You can use something like https://htmlcolorcodes.com/ to pick your color and then copy the hex value, in this example it would be 0x0ED9EE

Background Image

If you would like to create your own background, awesome! You'll want to save the file with these specifications:

  • 320 x 240 pixels
  • 16-bit RGB color (8-bits per channel)
  • Save file as .bmp format

You can then copy the .bmp file to the root level of the CIRCUITPY drive. Make sure you refer to this new filename in the pyportal constructor line:

default_bg=cwd+"/bitcoin_background.bmp"

Change that line to use the new filename name, such as:

default_bg=cwd+"/my_new_background.bmp"

Bitcoin Wallet Display

Total Bitcoin Wallet Value Variant

If you'd like to have your PyPortal Bitcoin Display do some math for you and add up the total value of your Bitcoin wallet, based on the current Bitcoin Price Index value, no problem!

This variation on the code does just that!

"""
This example will access the coindesk API, grab a number like bitcoin value in
USD, multiply it by your # of bitcoins and display it on a screen
If you can find something that spits out JSON data, we can display it!
"""
import time
import board
from adafruit_pyportal import PyPortal

# You can display in 'GBP', 'EUR' or 'USD'
CURRENCY = 'USD'
NUM_BITCOINS = 3.14    # how many bitcoins to display
# Set up where we'll be fetching data from
DATA_SOURCE = "https://api.coindesk.com/v1/bpi/currentprice.json"
DATA_LOCATION = ['bpi', CURRENCY, 'rate_float']

# We will convert the value from coindesk into a string that calculates our
# total bitcoin value!
def text_transform(val):
    format_str = "{:,.2f} Bitcoins\n = {:,d}"
    if CURRENCY == 'USD':
        format_str = "{:,.2f} Bitcoins\n = ${:,d}"
    if CURRENCY == 'EUR':
        format_str = "{:,.2f} Bitcoins\n = €{:,d}"
    if CURRENCY == 'GBP':
        format_str = "{:,.2f} Bitcoins\n = £{:,d}"
    return format_str.format(NUM_BITCOINS, int(val*NUM_BITCOINS))

# the current working directory (where this file is)
cwd = ("/"+__file__).rsplit('/', 1)[0]
pyportal = PyPortal(url=DATA_SOURCE, json_path=DATA_LOCATION,
                    status_neopixel=board.NEOPIXEL,
                    default_bg=cwd+"/bitcoin_background.bmp",
                    text_font=cwd+"/fonts/Arial-BoldItalic-12-Complete.bdf",
                    text_position=(192, 130),
                    text_color=0x0,
                    text_transform=text_transform)
pyportal.preload_font()  # preload alphanums
pyportal.preload_font((0x00A3, 0x20AC)) # preload gbp/euro symbol

while True:
    try:
        value = pyportal.fetch()
        print("Response is", value)
    except (ValueError, RuntimeError) as e:
        print("Some error occured, retrying! -", e)

    time.sleep(3*60)  # wait 3 minutes

If you've already set things up based on the instructions on the previous page for the simple bitcoin.py example, you can now copy this new code and paste it into Mu, then save it as code.py on your PyPortal, overwriting the existing version.

This one works nearly identically, with a few small changes.

First, there is now a NUM_BITCOINS variable. Change this to represent the number of Bitcoins in your wallet. 

NUM_BITCOINS = 3.14

Second, the text_transform() function now does more than just format your text to include the currency symbol. It also multiplies the Bitcoin value in your chosen currency by the NUM_BITCOINS value to give you your grand total!

Download: file
def text_transform(val):
    format_str = "{:,.2f} Bitcoins\n = {:,d}"
    if CURRENCY == 'USD':
        format_str = "{:,.2f} Bitcoins\n = ${:,d}"
    if CURRENCY == 'EUR':
        format_str = "{:,.2f} Bitcoins\n = €{:,d}"
    if CURRENCY == 'GBP':
        format_str = "{:,.2f} Bitcoins\n = £{:,d}"
    return format_str.format(NUM_BITCOINS, int(val*NUM_BITCOINS))

This also does a more sophisticated text string formatting job so that the result looks something like this:

         3.14 Bitcoins

            = $12,343

And, we're also specifying a smaller font so that it will fit the screen properly.

This guide was first published on Mar 26, 2019. It was last updated on Mar 26, 2019.