buttons: Add initial support for detecting button presses

Add mcu support for periodically polling for a button press.  Add host
code support for registering buttons and invoking callbacks for them.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/buttons.py

@@ -0,0 +1,143 @@
+# Support for button detection and callbacks
+#
+# Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import logging
+
+QUERY_TIME = .002
+RETRANSMIT_COUNT = 50
+
+
+######################################################################
+# Button state tracking
+######################################################################
+
+class MCU_buttons:
+    def __init__(self, printer, mcu):
+        self.reactor = printer.get_reactor()
+        self.mcu = mcu
+        mcu.add_config_object(self)
+        self.pin_list = []
+        self.callbacks = []
+        self.invert = self.last_button = 0
+        self.ack_cmd = None
+        self.ack_count = 0
+    def setup_buttons(self, pins, callback):
+        mask = 0
+        shift = len(self.pin_list)
+        for pin_params in pins:
+            if pin_params['invert']:
+                self.invert |= 1 << len(self.pin_list)
+            mask |= 1 << len(self.pin_list)
+            self.pin_list.append((pin_params['pin'], pin_params['pullup']))
+        self.callbacks.append((mask, shift, callback))
+    def build_config(self):
+        if not self.pin_list:
+            return
+        self.oid = self.mcu.create_oid()
+        self.mcu.add_config_cmd("config_buttons oid=%d button_count=%d" % (
+            self.oid, len(self.pin_list)))
+        for i, (pin, pull_up) in enumerate(self.pin_list):
+            self.mcu.add_config_cmd(
+                "buttons_add oid=%d pos=%d pin=%s pull_up=%d" % (
+                    self.oid, i, pin, pull_up), is_init=True)
+        cmd_queue = self.mcu.alloc_command_queue()
+        self.ack_cmd = self.mcu.lookup_command(
+            "buttons_ack oid=%c count=%c", cq=cmd_queue)
+        clock = self.mcu.get_query_slot(self.oid)
+        rest_ticks = self.mcu.seconds_to_clock(QUERY_TIME)
+        self.mcu.add_config_cmd(
+            "buttons_query oid=%d clock=%d rest_ticks=%d retransmit_count=%d" % (
+                self.oid, clock, rest_ticks, RETRANSMIT_COUNT), is_init=True)
+        self.mcu.register_msg(
+            self.handle_buttons_state, "buttons_state", self.oid)
+    def handle_buttons_state(self, params):
+        # Expand the message ack_count from 8-bit
+        ack_count = self.ack_count
+        ack_diff = (ack_count - params['ack_count']) & 0xff
+        if ack_diff & 0x80:
+            ack_diff -= 0x100
+        msg_ack_count = ack_count - ack_diff
+        # Determine new buttons
+        buttons = params['state']
+        new_count = msg_ack_count + len(buttons) - self.ack_count
+        if new_count <= 0:
+            return
+        new_buttons = buttons[-new_count:]
+        # Send ack to MCU
+        self.ack_cmd.send([self.oid, new_count])
+        self.ack_count += new_count
+        # Call self.handle_button() with this event in main thread
+        for b in new_buttons:
+            self.reactor.register_async_callback(
+                (lambda e, s=self, b=ord(b): s.handle_button(e, b)))
+    def handle_button(self, eventtime, button):
+        button ^= self.invert
+        changed = button ^ self.last_button
+        for mask, shift, callback in self.callbacks:
+            if changed & mask:
+                callback(eventtime, (button & mask) >> shift)
+        self.last_button = button
+
+
+######################################################################
+# Rotary Encoders
+######################################################################
+
+class RotaryEncoder:
+    def __init__(self, cw_callback, ccw_callback):
+        self.cw_callback = cw_callback
+        self.ccw_callback = ccw_callback
+        self.next_callback = None
+    def encoder_callback(self, eventtime, state):
+        # XXX - do full encoder state tracking
+        if state == 3:
+            self.next_callback = None
+        elif state == 2:
+            self.next_callback = self.ccw_callback
+        elif state == 1:
+            self.next_callback = self.cw_callback
+        elif self.next_callback is not None:
+            self.next_callback(eventtime)
+            self.next_callback = None
+
+
+######################################################################
+# Button registration code
+######################################################################
+
+class PrinterButtons:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.mcu_buttons = {}
+    def register_buttons(self, pins, callback):
+        # Parse pins
+        ppins = self.printer.lookup_object('pins')
+        mcu = mcu_name = None
+        pin_params_list = []
+        for pin in pins:
+            pin_params = ppins.lookup_pin('digital_in', pin)
+            if mcu is not None and pin_params['chip'] != mcu:
+                raise ppins.error("button pins must be on same mcu")
+            mcu = pin_params['chip']
+            mcu_name = pin_params['chip_name']
+            pin_params_list.append(pin_params)
+        # Register pins and callback with the appropriate MCU
+        mcu_buttons = self.mcu_buttons.get(mcu_name)
+        if (mcu_buttons is None
+            or len(mcu_buttons.pin_list) + len(pin_params_list) > 8):
+            self.mcu_buttons[mcu_name] = mcu_buttons = MCU_buttons(
+                self.printer, mcu)
+        mcu_buttons.setup_buttons(pin_params_list, callback)
+    def register_rotary_encoder(self, pin1, pin2, cw_callback, ccw_callback):
+        re = RotaryEncoder(cw_callback, ccw_callback)
+        self.register_buttons([pin1, pin2], re.encoder_callback)
+    def register_button_push(self, pin, callback):
+        def helper(eventtime, state, callback=callback):
+            if state:
+                callback(eventtime)
+        self.register_buttons([pin], helper)
+
+def load_config(config):
+    return PrinterButtons(config)