Like the hardware, the software is very modular:
- Overall setup, and control, including handling the rotary encoder
- A class representing a directory on the SD card with the ability to navigate up and down the tree
- A class to manage the emulator
- A helper class to properly debounce the encoder push switch (this is usable for any use of input switches)
Main
Main is simple enough:
- Initialize things
- Helper functions
- Loop, handling the rotary encoder and its switch and using the results to manipulate the current directory node and the emulator
"""
The MIT License (MIT)
Copyright (c) 2018 Dave Astels
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.
--------------------------------------------------------------------------------
EPROM emulator UI in CircuitPython.
Targeted for the SAMD51 boards.
by Dave Astels
"""
import adafruit_sdcard
import adafruit_ssd1306
import board
import busio
import digitalio
import storage
from debouncer import Debouncer
from directory_node import DirectoryNode
from emulator import Emulator
# pylint: disable=global-statement
# --------------------------------------------------------------------------------
# Initialize Rotary encoder
# Encoder button is a digital input with pullup on D2
button = Debouncer(board.D2, digitalio.Pull.UP, 0.01)
# Rotary encoder inputs with pullup on D3 & D4
rot_a = digitalio.DigitalInOut(board.D4)
rot_a.direction = digitalio.Direction.INPUT
rot_a.pull = digitalio.Pull.UP
rot_b = digitalio.DigitalInOut(board.D3)
rot_b.direction = digitalio.Direction.INPUT
rot_b.pull = digitalio.Pull.UP
# --------------------------------------------------------------------------------
# Initialize I2C and OLED
i2c = busio.I2C(board.SCL, board.SDA)
oled = adafruit_ssd1306.SSD1306_I2C(128, 32, i2c)
oled.fill(0)
oled.text("Initializing SD", 0, 10)
oled.show()
# --------------------------------------------------------------------------------
# Initialize SD card
# SD_CS = board.D10
# Connect to the card and mount the filesystem.
spi = busio.SPI(board.D13, board.D11, board.D12) # SCK, MOSI, MISO
cs = digitalio.DigitalInOut(board.D10)
sdcard = adafruit_sdcard.SDCard(spi, cs)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, "/sd")
oled.fill(0)
oled.text("Done", 0, 10)
oled.show()
# --------------------------------------------------------------------------------
# Initialize globals
encoder_counter = 0
encoder_direction = 0
# constants to help us track what edge is what
A_POSITION = 0
B_POSITION = 1
UNKNOWN_POSITION = -1 # initial state so we know if something went wrong
rising_edge = falling_edge = UNKNOWN_POSITION
PROGRAM_MODE = 0
EMULATE_MODE = 1
current_mode = PROGRAM_MODE
emulator = Emulator(i2c)
# --------------------------------------------------------------------------------
# Helper functions
def is_binary_name(filename):
return filename[-4:] == ".bin"
def load_file(filename):
data = []
with open(filename, "rb") as f:
data = f.read()
return data
def display_emulating_screen():
oled.fill(0)
oled.text("Emulating", 0, 0)
oled.text(current_dir.selected_filename, 0, 10)
oled.show()
# pylint: disable=global-statement
def emulate():
global current_mode
data = load_file(current_dir.selected_filepath)
emulator.load_ram(data)
emulator.enter_emulate_mode()
current_mode = EMULATE_MODE
display_emulating_screen()
# pylint: disable=global-statement
def program():
global current_mode
emulator.enter_program_mode()
current_mode = PROGRAM_MODE
current_dir.force_update()
# --------------------------------------------------------------------------------
# Main loop
current_dir = DirectoryNode(oled, name="/sd")
current_dir.force_update()
rising_edge = falling_edge = UNKNOWN_POSITION
rotary_prev_state = [rot_a.value, rot_b.value]
while True:
# reset encoder and wait for the next turn
encoder_direction = 0
# take a 'snapshot' of the rotary encoder state at this time
rotary_curr_state = [rot_a.value, rot_b.value]
# See https://learn.adafruit.com/media-dial/code
if rotary_curr_state != rotary_prev_state:
print("Was: {}".format(rotary_prev_state))
print("Now: {}".format(rotary_curr_state))
if rotary_prev_state == [True, True]:
if not rotary_curr_state[A_POSITION]:
print("Falling A")
falling_edge = A_POSITION
elif not rotary_curr_state[B_POSITION]:
print("Falling B")
falling_edge = B_POSITION
else:
continue
if rotary_curr_state == [True, True]:
if not rotary_prev_state[B_POSITION]:
rising_edge = B_POSITION
print("Rising B")
elif not rotary_prev_state[A_POSITION]:
rising_edge = A_POSITION
print("Rising A")
else:
continue
# check first and last edge
if (rising_edge == A_POSITION) and (falling_edge == B_POSITION):
encoder_counter -= 1
encoder_direction = -1
print("%d dec" % encoder_counter)
elif (rising_edge == B_POSITION) and (falling_edge == A_POSITION):
encoder_counter += 1
encoder_direction = 1
print("%d inc" % encoder_counter)
else:
# (shrug) something didn't work out, oh well!
encoder_direction = 0
# reset our edge tracking
rising_edge = falling_edge = UNKNOWN_POSITION
rotary_prev_state = rotary_curr_state
# Handle encoder rotation
if current_mode == PROGRAM_MODE: # Ignore rotation if in EMULATE mode
if encoder_direction == -1:
current_dir.up()
elif encoder_direction == 1:
current_dir.down()
# look for a press of the rotary encoder switch press, with debouncing
button.update()
if button.fell:
if current_mode == EMULATE_MODE:
program()
elif is_binary_name(current_dir.selected_filename):
emulate()
else:
current_dir = current_dir.click()
Directories
The DirectoryNode class provides the ability to navigate a file system. It was written with an SD filesystem in mind, but just relies on the os module so should work with any storage that os uses.
The class provides public properties to get the name and full path of the selected file, as well as methods to force a screen update, move up and down in the displayed list, and do the appropriate thing in response to a selection event (in this case pushing the rotary encoder's switch).
When you create the root level instance, you provide an oled instance to display on, as well as the name of the root (which defaults to "/").
i2c = busio.I2C(board.SCL, board.SDA) oled = adafruit_ssd1306.SSD1306_I2C(128, 32, i2c) ... vfs = storage.VfsFat(sdcard) storage.mount(vfs, "/sd") ... current_dir = DirectoryNode(oled, name="/sd") current_dir.force_update()
Use of the DirectoryNode is straightforward as well, We can call up(), down(), and click() in response to activity on the rotary encoder, the DirectoryNode instance takes care of maintaining the display:
if current_mode == PROGRAM_MODE: # Ignore rotation if in EMULATE mode
if encoder_direction == -1:
current_dir.up()
elif encoder_direction == 1:
current_dir.down()
# look for a press of the rotary encoder switch press, with debouncing
button.update()
if button.fell:
if current_mode == EMULATE_MODE:
program()
elif is_binary_name(current_dir.selected_filename):
emulate()
else:
current_dir = current_dir.click()
Notice that the click() method returns a DirectoryNode which is assigned to the current node. That's because clicking could result in moving to a child or parent directory.
"""
The MIT License (MIT)
Copyright (c) 2018 Dave Astels
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.
--------------------------------------------------------------------------------
Manage a directory in the file system.
"""
import os
class DirectoryNode:
"""Display and navigate the SD card contents"""
def __init__(self, display, parent=None, name="/"):
"""Initialize a new instance.
:param adafruit_ssd1306.SSD1306 on: the OLED instance to display on
:param DirectoryNode below: optional parent directory node
:param string named: the optional name of the new node
"""
self.display = display
self.parent = parent
self.name = name
self.files = []
self.top_offset = 0
self.old_top_offset = -1
self.selected_offset = 0
self.old_selected_offset = -1
def __cleanup(self):
"""Dereference things for speedy gc."""
self.display = None
self.parent = None
self.name = None
self.files = None
return self
@staticmethod
def __is_dir(path):
"""Determine whether a path identifies a machine code bin file.
:param string path: path of the file to check
"""
if path[-2:] == "..":
return False
try:
os.listdir(path)
return True
except OSError:
return False
@staticmethod
def __sanitize(name):
"""Nondestructively strip off a trailing slash, if any, and return the result.
:param string name: the filename
"""
if name[-1] == "/":
return name[:-1]
return name
# pylint: disable=protected-access
def __path(self):
"""Return the result of recursively follow the parent links, building a full
path to this directory."""
if self.parent:
return self.parent.__path() + os.sep + self.__sanitize(self.name)
return self.__sanitize(self.name)
def __make_path(self, filename):
"""Return a full path to the specified file in this directory.
:param string filename: the name of the file in this directory
"""
return self.__path() + os.sep + filename
def __number_of_files(self):
"""The number of files in this directory, including the ".." for the parent
directory if this isn't the top directory on the SD card."""
self.__get_files()
return len(self.files)
def __get_files(self):
"""Return a list of the files in this directory.
If this is not the top directory on the SD card, a
".." entry is the first element.
Any directories have a slash appended to their name."""
if len(self.files) == 0:
self.files = os.listdir(self.__path())
self.files.sort()
if self.parent:
self.files.insert(0, "..")
for index, name in enumerate(self.files, start=1):
if self.__is_dir(self.__make_path(name)):
self.files[index] = name + "/"
def __update_display(self):
"""Update the displayed list of files if required."""
if self.top_offset != self.old_top_offset:
self.__get_files()
self.display.fill(0)
min_offset = min(self.top_offset + 4, self.__number_of_files())
for i in range(self.top_offset, min_offset):
self.display.text(self.files[i], 10, (i - self.top_offset) * 8)
self.display.show()
self.old_top_offset = self.top_offset
def __update_selection(self):
"""Update the selected file lighlight if required."""
if self.selected_offset != self.old_selected_offset:
if self.old_selected_offset > -1:
old_offset = (self.old_selected_offset - self.top_offset) * 8
self.display.text(">", 0, old_offset, 0)
new_offset = (self.selected_offset - self.top_offset) * 8
self.display.text(">", 0, new_offset, 1)
self.display.show()
self.old_selected_offset = self.selected_offset
@staticmethod
def __is_directory_name(filename):
"""Is a filename the name of a directory.
:param string filename: the name of the file
"""
return filename[-1] == '/'
@property
def selected_filename(self):
"""The name of the currently selected file in this directory."""
self.__get_files()
return self.files[self.selected_offset]
@property
def selected_filepath(self):
"""The full path of the currently selected file in this directory."""
return self.__make_path(self.selected_filename)
def force_update(self):
"""Force an update of the file list and selected file highlight."""
self.old_selected_offset = -1
self.old_top_offset = -1
self.__update_display()
self.__update_selection()
def down(self):
"""Move down in the file list if possible, adjusting the selected file
indicator and scrolling the display as required."""
if self.selected_offset < self.__number_of_files() - 1:
self.selected_offset += 1
if self.selected_offset == self.top_offset + 4:
self.top_offset += 1
self.__update_display()
self.__update_selection()
def up(self):
"""Move up in the file list if possible, adjusting the selected file indicator
and scrolling the display as required."""
if self.selected_offset > 0:
self.selected_offset -= 1
if self.selected_offset < self.top_offset:
self.top_offset -= 1
self.__update_display()
self.__update_selection()
def click(self):
"""Handle a selection and return the new current directory.
If the selected file is the parent, i.e. "..", return to the parent
directory.
If the selected file is a directory, go into it."""
if self.selected_filename == "..":
if self.parent:
p = self.parent
p.force_update()
self.__cleanup()
return p
elif self.__is_directory_name(self.selected_filename):
new_node = DirectoryNode(
self.display, self, self.selected_filename)
new_node.force_update()
return new_node
return self
Emulator
The emulator class manages the emulator circuit. Its public interface is simple enough:
- enter program mode, to allow the RAM to be loaded
- enter emulation mode, giving control of the emulator RAM to the host
- load the emulator RAM with data
The load_ram method takes care of the controlling the the address counters and multiplexers. By decomposing into a handful of private methods, the class is quite straight forward:
"""
The MIT License (MIT)
Copyright (c) 2018 Dave Astels
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.
--------------------------------------------------------------------------------
Manage the emulator hardware.
"""
import adafruit_mcp230xx
import digitalio
# control pin values
PROGRAMMER_USE = False
EMULATE_USE = True
WRITE_ENABLED = False
WRITE_DISABLED = True
CHIP_ENABLED = False
CHIP_DISABLED = True
CLOCK_ACTIVE = False
CLOCK_INACTIVE = True
RESET_INACTIVE = False
RESET_ACTIVE = True
LED_OFF = False
LED_ON = True
ENABLE_HOST_ACCESS = False
DISABLE_HOST_ACCESS = True
class Emulator:
"""Handle all interaction with the emulator circuit."""
def __init__(self, i2c):
self.mcp = adafruit_mcp230xx.MCP23017(i2c)
self.mcp.iodir = 0x0000 # Make all pins outputs
# Configure the individual control pins
self.mode_pin = self.mcp.get_pin(8)
self.mode_pin.direction = digitalio.Direction.OUTPUT
self.mode_pin.value = PROGRAMMER_USE
self.write_pin = self.mcp.get_pin(9)
self.write_pin.direction = digitalio.Direction.OUTPUT
self.write_pin.value = WRITE_DISABLED
self.chip_select_pin = self.mcp.get_pin(10)
self.chip_select_pin.direction = digitalio.Direction.OUTPUT
self.chip_select_pin.value = CHIP_DISABLED
self.address_clock_pin = self.mcp.get_pin(11)
self.address_clock_pin.direction = digitalio.Direction.OUTPUT
self.address_clock_pin.value = CLOCK_INACTIVE
self.clock_reset_pin = self.mcp.get_pin(12)
self.clock_reset_pin.direction = digitalio.Direction.OUTPUT
self.clock_reset_pin.value = RESET_INACTIVE
self.led_pin = self.mcp.get_pin(13)
self.led_pin.direction = digitalio.Direction.OUTPUT
self.led_pin.value = False
def __pulse_write(self):
self.write_pin.value = WRITE_ENABLED
self.write_pin.value = WRITE_DISABLED
def __deactivate_ram(self):
self.chip_select_pin.value = CHIP_DISABLED
def __activate_ram(self):
self.chip_select_pin.value = CHIP_ENABLED
def __reset_address_counter(self):
self.clock_reset_pin.value = RESET_ACTIVE
self.clock_reset_pin.value = RESET_INACTIVE
def __advance_address_counter(self):
self.address_clock_pin.value = CLOCK_ACTIVE
self.address_clock_pin.value = CLOCK_INACTIVE
def __output_on_port_a(self, data_byte):
"""A hack to get around the limitation of the 23017
library to use 8-bit ports"""
self.mcp.gpio = (self.mcp.gpio & 0xFF00) | (data_byte & 0x00FF)
def enter_program_mode(self):
"""Enter program mode, allowing loading of the emulator RAM."""
self.mode_pin.value = PROGRAMMER_USE
self.led_pin.value = LED_OFF
def enter_emulate_mode(self):
"""Enter emulate mode, giving control of the emulator
ram to the host."""
self.mode_pin.value = EMULATE_USE
self.led_pin.value = LED_ON
def load_ram(self, code):
"""Load the emulator RAM. Automatically switched to program mode.
:param [byte] code: the list of bytes to load into the emulator RAM
"""
self.enter_program_mode()
self.__reset_address_counter()
for data_byte in code:
self.__output_on_port_a(data_byte)
self.__activate_ram()
self.__pulse_write()
self.__deactivate_ram()
self.__advance_address_counter()
Debouncer
I was having trouble with the encoder switch being deterministic, so decided to put some proper debouncing in place. I've had great success with the Bounce2 class in C++ but couldn't find a good Python version. So, I ported it:
"""
The MIT License (MIT)
Copyright (c) 2018 Dave Astels
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.
--------------------------------------------------------------------------------
Debounce an input pin.
"""
import time
import digitalio
class Debouncer:
"""Debounce an input pin"""
DEBOUNCED_STATE = 0x01
UNSTABLE_STATE = 0x02
CHANGED_STATE = 0x04
def __init__(self, pin, mode=None, interval=0.010):
"""Make am instance.
:param int pin: the pin (from board) to debounce
:param int mode: digitalio.Pull.UP or .DOWN (default is no
pull up/down)
:param int interval: bounce threshold in seconds (default is 0.010,
i.e. 10 milliseconds)
"""
self.state = 0x00
self.pin = digitalio.DigitalInOut(pin)
self.pin.direction = digitalio.Direction.INPUT
if mode is not None:
self.pin.pull = mode
if self.pin.value:
self.__set_state(Debouncer.DEBOUNCED_STATE |
Debouncer.UNSTABLE_STATE)
self.previous_time = 0
if interval is None:
self.interval = 0.010
else:
self.interval = interval
def __set_state(self, bits):
self.state |= bits
def __unset_state(self, bits):
self.state &= ~bits
def __toggle_state(self, bits):
self.state ^= bits
def __get_state(self, bits):
return (self.state & bits) != 0
def update(self):
"""Update the debouncer state. Must be called before using any of
the properties below"""
self.__unset_state(Debouncer.CHANGED_STATE)
current_state = self.pin.value
if current_state != self.__get_state(Debouncer.UNSTABLE_STATE):
self.previous_time = time.monotonic()
self.__toggle_state(Debouncer.UNSTABLE_STATE)
else:
if time.monotonic() - self.previous_time >= self.interval:
debounced_state = self.__get_state(Debouncer.DEBOUNCED_STATE)
if current_state != debounced_state:
self.previous_time = time.monotonic()
self.__toggle_state(Debouncer.DEBOUNCED_STATE)
self.__set_state(Debouncer.CHANGED_STATE)
@property
def value(self):
"""Return the current debounced value of the input."""
return self.__get_state(Debouncer.DEBOUNCED_STATE)
@property
def rose(self):
"""Return whether the debounced input went from low to high at
the most recent update."""
return self.__get_state(self.DEBOUNCED_STATE) \
and self.__get_state(self.CHANGED_STATE)
@property
def fell(self):
"""Return whether the debounced input went from high to low at
the most recent update."""
return (not self.__get_state(self.DEBOUNCED_STATE)) \
and self.__get_state(self.CHANGED_STATE)
As you can see, it's pretty simple to use, with the details hidden in private methods. Here's how it's used for the encoder switch:
button = Debouncer(board.D2, digitalio.Pull.UP, 0.01)
...
while True:
...
button.update()
if button.fell:
if current_mode == EMULATE_MODE:
program()
elif is_binary_name(current_dir.selected_filename):
emulate()
else:
current_dir = current_dir.click()
