Adafruit SPI devices which use the Adafruit Python GPIO library (i.e. are designed to work with the Raspberry Pi and BeagleBone Black) can easily be configured to work with the FT232H over a SPI connection. Some of these devices include:
Wiring
To use one of these devices you'll first want to first read the device's tutorial to get an overview of its connections and library usage. Then connect the device to the FT232H breakout just like you're connecting the device to a Raspberry Pi or BeagleBone Black, but with the following SPI connections:
- Device SCLK or clock to FT232H D0 / serial clock.
- Device MOSI or data in to FT232H D1 / serial output.
- Device MISO or data out to FT232H D2 / serial input.
For other digital pins on the device, such as chip select, reset, data, etc., you should connect those pins to any free GPIO pins on the FT232H, such as C0 to C7 (GPIO numbers 8 to 15).
For device power you can use the 5V pin on the FT232H board to supply up to ~500mA of 5 volt power. Also remember the FT232H board digital outputs operate at 3.3 volts and the digital inputs can safely accept either 3.3 volts or 5 volts.
Software Setup
Follow the device's tutorial and make sure you have installed on your PC any external Python libraries that the device uses For most devices like sensors there are no other Python dependencies to install.
Python Imaging Library For Displays
Many of the display libraries, such as the Nokia LCD, SSD1306, or ILI9341 display, use the Python imaging library (PIL) which you'll need to install on your PC. On a Windows PC it can be a little tricky to install Python libraries so I recommend installing the PIL setup executable from its website. On a Mac you'll need to make sure Xcode command line tools and PIP are installed, then run:
sudo pip install pil
or
sudo pip install pillow
On a Debian or Ubuntu Linux machine you can install PIL with an apt package by running:
sudo apt-get update sudo apt-get install python-imaging
After any dependencies are installed you can install the device's software library just like you were installing it on a Raspberry Pi or BeagleBone Black. You should run the software library's setup.py script and pass it the install parameter. For example on a Mac or Linux machine, in a command terminal navigate to the directory with the library's source code and execute:
sudo python setup.py install
On a Windows machine open a command terminal, navigate to the directory with the library's source code and execute:
python setup.py install
(make sure Python is added to your path before running the above!)
Usage
To make the device's example code work with the FT232H you'll need to make a few small changes. First you'll need to include the FT232H module, enable the FT232H, and create an FT232H device by adding to the start of the code:
import Adafruit_FT232H as FT232H # Temporarily disable FTDI serial drivers to use the FT232H device. FT232H.use_FT232H() # Create an FT232H device instance. ft232h = FT232H.FT232H()
Next create an FT232H SPI object using the FT232H device. Note that you can optionally set the chip select / secondary select pin by specifying the FT232H GPIO number that's connected to the device's chip select pin.
For example if the device's chip select pin is connected to the FT232H GPIO 8 / C0 pin the SPI device would look like:
# Create an FT232H SPI object with the specified chip select pin. ft232h_spi = FT232H.SPI(ft232h, cs=8)
Finally create the device object and pass in the FT232H SPI device that was created above as the spi parameter of the initializer. If the device uses other GPIO pins, such as a reset or data pin, you'll also need to pass the FT232H device as the gpio parameter value.
For example to configure a Nokia LCD with the data / DC pin connected to FT232H GPIO 9 / C1 and the reset pin connected to FT232H GPIO 10 / C2, the code would look like:
display = LCD.PCD8544(9, 10, spi=ft232h_spi, gpio=ft232h)
Putting everything together, here's the full Nokia LCD shapes.py example converted over to use the FT232H with the chip select / CS pin connected to GPIO 8 / C0, data / DC pin connected to GPIO 9 / C1, the reset / RST pin connected to GPIO10 / C2:
import time
import Adafruit_Nokia_LCD as LCD
import Adafruit_FT232H as FT232H
from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont
# Temporarily disable FTDI serial drivers to use the FT232H device.
FT232H.use_FT232H()
# Create an FT232H device instance.
ft232h = FT232H.FT232H()
# Create an FT232H SPI object with the specified chip select pin.
ft232h_spi = FT232H.SPI(ft232h, cs=8)
# Create the Nokia display object.
disp = LCD.PCD8544(9, 10, spi=ft232h_spi, gpio=ft232h)
# The code below is exactly the same as the Nokia LCD library's shapes.py example:
# Initialize library.
disp.begin(contrast=60)
# Clear display.
disp.clear()
disp.display()
# Create blank image for drawing.
# Make sure to create image with mode '1' for 1-bit color.
image = Image.new('1', (LCD.LCDWIDTH, LCD.LCDHEIGHT))
# Get drawing object to draw on image.
draw = ImageDraw.Draw(image)
# Draw a white filled box to clear the image.
draw.rectangle((0,0,LCD.LCDWIDTH,LCD.LCDHEIGHT), outline=255, fill=255)
# Draw some shapes.
draw.ellipse((2,2,22,22), outline=0, fill=255)
draw.rectangle((24,2,44,22), outline=0, fill=255)
draw.polygon([(46,22), (56,2), (66,22)], outline=0, fill=255)
draw.line((68,22,81,2), fill=0)
draw.line((68,2,81,22), fill=0)
# Load default font.
font = ImageFont.load_default()
# Alternatively load a TTF font.
# Some nice fonts to try: http://www.dafont.com/bitmap.php
# font = ImageFont.truetype('Minecraftia.ttf', 8)
# Write some text.
draw.text((8,30), 'Hello World!', font=font)
# Display image.
disp.image(image)
disp.display()
print 'Press Ctrl-C to quit.'
while True:
time.sleep(1.0)
Page last edited March 08, 2024
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