105 lines
4.3 KiB
C
105 lines
4.3 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "shared-bindings/neopixel_write/__init__.h"
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#include "bindings/rp2pio/StateMachine.h"
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#include "common-hal/rp2pio/StateMachine.h"
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#include "shared-bindings/microcontroller/__init__.h"
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#include "shared-bindings/digitalio/DigitalInOut.h"
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#include "supervisor/port.h"
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uint64_t next_start_raw_ticks = 0;
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// NeoPixels are 800khz bit streams. We are choosing zeros as <312ns hi, 936 lo> and ones
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// and ones as <700 ns hi, 556 ns lo>.
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// cycle. The first two instructions always run while only one of the two final
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// instructions run per bit. We start with the low period because it can be
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// longer while waiting for more data.
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const uint16_t neopixel_program[] = {
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// bitloop:
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// out x 1 side 0 [6]; Drive low. Side-set still takes place before instruction stalls.
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0x6621,
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// jmp !x do_zero side 1 [3]; Branch on the bit we shifted out previous delay. Drive high.
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0x1323,
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// do_one:
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// jmp bitloop side 1 [4]; Continue driving high, for a one (long pulse)
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0x1400,
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// do_zero:
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// nop side 0 [4]; Or drive low, for a zero (short pulse)
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0xa442
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};
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void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout, uint8_t *pixels, uint32_t num_bytes) {
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// Set everything up.
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rp2pio_statemachine_obj_t state_machine;
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// TODO: Cache the state machine after we create it once. We'll need a way to
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// change the pins then though.
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uint32_t pins_we_use = 1 << digitalinout->pin->number;
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bool ok = rp2pio_statemachine_construct(&state_machine,
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neopixel_program, sizeof(neopixel_program) / sizeof(neopixel_program[0]),
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12800000, // MHz, to get about appropriate sub-bit times in PIO program.
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NULL, 0, // init program
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NULL, 1, // out
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NULL, 1, // in
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0, 0, // in pulls
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NULL, 1, // set
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digitalinout->pin, 1, // sideset
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0, pins_we_use, // initial pin state
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NULL, // jump pin
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pins_we_use, true, false,
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true, 8, false, // TX, auto pull every 8 bits. shift left to output msb first
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true, // Wait for txstall. If we don't, then we'll deinit too quickly.
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false, 32, true, // RX setting we don't use
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false, // claim pins
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false, // Not user-interruptible.
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false, // No sideset enable
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0, -1); // wrap
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if (!ok) {
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// Do nothing. Maybe bitbang?
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return;
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}
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// Wait to make sure we don't append onto the last transmission. This should only be a tick or
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// two.
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while (port_get_raw_ticks(NULL) < next_start_raw_ticks) {
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}
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common_hal_rp2pio_statemachine_write(&state_machine, pixels, num_bytes, 1 /* stride in bytes */);
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// Use a private deinit of the state machine that doesn't reset the pin.
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rp2pio_statemachine_deinit(&state_machine, true);
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// Reset the pin and release it from the PIO
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gpio_init(digitalinout->pin->number);
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common_hal_digitalio_digitalinout_switch_to_output((digitalio_digitalinout_obj_t *)digitalinout, false, DRIVE_MODE_PUSH_PULL);
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// Update the next start to +2 ticks. This ensures we give it at least 300us.
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next_start_raw_ticks = port_get_raw_ticks(NULL) + 2;
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}
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