Rasp-Hack-Led-Backpack-Sommaire

Sommaire

If you're interested in writing your own code, the easy way is to start with the examples in the code repository (the .py files starting with 'ex_'), but the following information may be helpful as well.

Adafruit_LEDBackpack

All of the low-level IO and I2C access is passed through Adafruit_LEDBackpack.py, which is used by all of the other classes and examples in the library. This file implements a class named LEDBackpack, which has the following functions:

setBrightness

setBrightness(brightness)

Sets the display brightness with a value between 0 and 15

setBlinkRate

setBlinkRate(blinkRate)

Sets the optional blink rate for the display, with one of the following values for blinkRate

• 0 = No Blinking
• 1 = Blink at 2Hz
• 2 = Blink at 1Hz
• 3 = Blink at 1/2 Hz

setBufferRow

setBufferRow(row, value)

Updates a single row of data. The HT16K33 contains an internal memory of 8 rows, with each row having 16 bits of data. Each row generally corresponds to one character on a 7-segment display or one row of pixels on an 8x8 display.

getBuffer

getBuffer()

Returns a list of 8 16-bit values representing the current state of the internal buffer, which can be used to update the display without affecting the rest of the content.

clear

clear()

Clears the contents of the entire buffer

Adafruit_7Segment

The 7-Segment library is encapsulated in the file Adafruit_7Segment.py, and implements a class named SevenSegment (since class names can't start with a digit). It instantiates and instance of Adafruit_LEDBackpack internally, and you normally won't need to use the lower level class directly. It implements the following functions:

writeDigitRaw

writeDigitRaw(charNumber, value)

This will raw a raw 16-bit value to the specified charNumber, which corresponds to a single row in the HT16K33, and one character in the 4x7-segment displays. (Note: row 2 is the colon on most 4 character displays). You can use this to display custom characters that aren't supported natively by the current library.

writeDigit

writeDigit(charNumber, value, dot=False)

Writes a single decimal (0..9) or hexadecimal (0..9 and A..F) character to the display, with charNumber being the character to update, and value being the digit. You can set a third optional argument, dot, to True to set the decimal place after each character.

setColon

setColon(state)

You can pass either True of False to this function to enable or disable the colon that is usually connected to row 2 of the HT16K33.

Adafruit_8x8.py

The Adafruit_8x8.py file implements a class names EightByEight that can be used to drive 8x8 pixel square LED blocks. It contains the following functions:

writeRowRaw

writeRowRaw(charNumber, value)

This will update an entire row of data with the specified 16-bit value (though normally only the last 8-bits are used on one-color 8x8 displays. This is faster than setting individual pixels.

setPixel

setPixel(x, y, color)

This function will update a single pixel within the relevant X/Y space of the display. Please keep in mind that lists in Python are zero-based, meaning to sets pixels 1..8 in each direction you actually use the values 0..7, so the following will enable the pixel 3 over and 5 down:

grid = EightByEight(address=0x70)
grid.setPixel(2, 4)</niwiki>

== Exemples ===
If you need a bit of help, simply looking at the provided example python code:

* '''ex_7segment_clock.py''': Displays the current time on a 4*7-segment display, changing the state of the colon every second
* '''ex_8x8_pixels.py''': Constantly updates every pixel on an 8x8 display, one pixel at a time.

You can run these examples with the following code: 

 <nowiki>sudo python ex_8x8_pixels.py

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Source: AdaFruit

Traduit avec l'autorisation d'AdaFruit Industries - Translated with the permission from Adafruit Industries - www.adafruit.com

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