Display something on SSD1306 when the button is pressed on Raspberry Pi 2.

rpi2_ssd1306.py

#!/usr/bin/env python3

# Copyright (c) 2019 OBONO
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import Adafruit_GPIO.SPI as SPI
import Adafruit_SSD1306
import RPi.GPIO as GPIO
import subprocess
import sys
import time

FONT_DATA = [ # import from "glcdfont.c"
    b"\x00\x00\x00\x00\x00", b"\x00\x00\x5f\x00\x00", b"\x00\x07\x00\x07\x00",
    b"\x14\x7f\x14\x7f\x14", b"\x24\x2a\x7f\x2a\x12", b"\x23\x13\x08\x64\x62",
    b"\x36\x49\x56\x20\x50", b"\x00\x08\x07\x03\x00", b"\x00\x1c\x22\x41\x00",
    b"\x00\x41\x22\x1c\x00", b"\x2a\x1c\x7f\x1c\x2a", b"\x08\x08\x3e\x08\x08",
    b"\x00\x80\x70\x30\x00", b"\x08\x08\x08\x08\x08", b"\x00\x00\x60\x60\x00",
    b"\x20\x10\x08\x04\x02", b"\x3e\x51\x49\x45\x3e", b"\x00\x42\x7f\x40\x00",
    b"\x72\x49\x49\x49\x46", b"\x21\x41\x49\x4d\x33", b"\x18\x14\x12\x7f\x10",
    b"\x27\x45\x45\x45\x39", b"\x3c\x4a\x49\x49\x31", b"\x41\x21\x11\x09\x07",
    b"\x36\x49\x49\x49\x36", b"\x46\x49\x49\x29\x1e", b"\x00\x00\x14\x00\x00",
    b"\x00\x40\x34\x00\x00", b"\x00\x08\x14\x22\x41", b"\x14\x14\x14\x14\x14",
    b"\x00\x41\x22\x14\x08", b"\x02\x01\x59\x09\x06", b"\x3e\x41\x5d\x59\x4e",
    b"\x7c\x12\x11\x12\x7c", b"\x7f\x49\x49\x49\x36", b"\x3e\x41\x41\x41\x22",
    b"\x7f\x41\x41\x41\x3e", b"\x7f\x49\x49\x49\x41", b"\x7f\x09\x09\x09\x01",
    b"\x3e\x41\x41\x51\x73", b"\x7f\x08\x08\x08\x7f", b"\x00\x41\x7f\x41\x00",
    b"\x20\x40\x41\x3f\x01", b"\x7f\x08\x14\x22\x41", b"\x7f\x40\x40\x40\x40",
    b"\x7f\x02\x1c\x02\x7f", b"\x7f\x04\x08\x10\x7f", b"\x3e\x41\x41\x41\x3e",
    b"\x7f\x09\x09\x09\x06", b"\x3e\x41\x51\x21\x5e", b"\x7f\x09\x19\x29\x46",
    b"\x26\x49\x49\x49\x32", b"\x03\x01\x7f\x01\x03", b"\x3f\x40\x40\x40\x3f",
    b"\x1f\x20\x40\x20\x1f", b"\x3f\x40\x38\x40\x3f", b"\x63\x14\x08\x14\x63",
    b"\x03\x04\x78\x04\x03", b"\x61\x59\x49\x4d\x43", b"\x00\x7f\x41\x41\x41",
    b"\x02\x04\x08\x10\x20", b"\x00\x41\x41\x41\x7f", b"\x04\x02\x01\x02\x04",
    b"\x40\x40\x40\x40\x40", b"\x00\x03\x07\x08\x00", b"\x20\x54\x54\x78\x40",
    b"\x7f\x28\x44\x44\x38", b"\x38\x44\x44\x44\x28", b"\x38\x44\x44\x28\x7f",
    b"\x38\x54\x54\x54\x18", b"\x00\x08\x7e\x09\x02", b"\x18\xa4\xa4\x9c\x78",
    b"\x7f\x08\x04\x04\x78", b"\x00\x44\x7d\x40\x00", b"\x20\x40\x40\x3d\x00",
    b"\x7f\x10\x28\x44\x00", b"\x00\x41\x7f\x40\x00", b"\x7c\x04\x78\x04\x78",
    b"\x7c\x08\x04\x04\x78", b"\x38\x44\x44\x44\x38", b"\xfc\x18\x24\x24\x18",
    b"\x18\x24\x24\x18\xfc", b"\x7c\x08\x04\x04\x08", b"\x48\x54\x54\x54\x24",
    b"\x04\x04\x3f\x44\x24", b"\x3c\x40\x40\x20\x7c", b"\x1c\x20\x40\x20\x1c",
    b"\x3c\x40\x30\x40\x3c", b"\x44\x28\x10\x28\x44", b"\x4c\x90\x90\x90\x7c",
    b"\x44\x64\x54\x4c\x44", b"\x00\x08\x36\x41\x00", b"\x00\x00\x77\x00\x00",
    b"\x00\x41\x36\x08\x00", b"\x02\x01\x02\x04\x02"
]
FONT_WIDTH = 6
BUTTON_PIN = 17
BOUNCE_TIME = 300
LOOP_WAIT = 5
DISP_COUNT_MAX = 6

### Custom class

class MySSD1306(Adafruit_SSD1306.SSD1306_128_64):

    def __init__(self):
        super().__init__(rst=None)

    def putstring(self, page, x, str):
        for c in str:
            if 0x20 <= c <= 0x7e:
                self.putchar(page, x, c)
                x += FONT_WIDTH
            elif c == 0x0a:
                page += 1
                x = 0

    def putchar(self, page, x, c):
        idx = page * self.width + x
        buffer_len = len(self._buffer)
        for b in FONT_DATA[c - 0x20]:
            if 0 <= idx < buffer_len: self._buffer[idx] = b
            idx += 1

    def on(self):
        self.command(Adafruit_SSD1306.SSD1306_DISPLAYON) 

    def off(self):
        self.command(Adafruit_SSD1306.SSD1306_DISPLAYOFF) 

### Callback function

def gpio_handler(gpio_pin):
    global disp, disp_count, script
    if disp_count == 0: disp.on()
    disp_count = DISP_COUNT_MAX
    disp.clear()
    text = subprocess.check_output(script)
    disp.putstring(0, 0, text)
    disp.display()

### Main procedure

disp = MySSD1306()
disp.begin()
disp.off()
disp_count = 0
script = sys.argv[1] if len(sys.argv) >= 2 else "date '+%T'"

GPIO.setmode(GPIO.BCM)
GPIO.setup(BUTTON_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.add_event_detect(BUTTON_PIN, GPIO.FALLING, callback=gpio_handler, bouncetime=BOUNCE_TIME)

try:
    while True:
        time.sleep(LOOP_WAIT)
        if disp_count > 0:
            disp_count -= 1
            if disp_count == 0: disp.off()
except KeyboardInterrupt:
    GPIO.cleanup()

~circuit_diagram.png

~README.md

rpi2_ssd1306.py

Description

Display something letters on SSD1306 when the button is pressed on Raspberry Pi 2.

Assumption

• I2C is enabled.
• python3 is installed.
• Devices are connected as in the diagram.

Prepareing

Install some necessary libraries.

$ sudo apt-get install python-rpi.gpio
$ git clone https://github.com/adafruit/Adafruit_Python_SSD1306.git
$ cd Adafruit_Python_SSD1306
$ sudo python3 setup.py install

Execution

For example, type following command.

$ sudo ./rpi2_ssd1306.py "echo 'Hello'"

"Hello" will be displayed when the button is pressed. The display will be turned off after about 30 seconds.

License

MIT