103 lines
3.5 KiB
C
103 lines
3.5 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) 2019 Lucian Copeland 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 "py/mperrno.h"
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#include "py/mphal.h"
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#include "py/runtime.h"
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#include "common-hal/microcontroller/Pin.h"
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#include "stm32f4xx_hal.h"
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#include "stm32f4xx_ll_gpio.h"
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#include "supervisor/port.h"
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uint64_t next_start_raw_ticks = 0;
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// sysclock divisors
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#define MAGIC_800_INT 900000 // ~1.11 us -> 1.2 field
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#define MAGIC_800_T0H 3500000 // 300ns actual; 880 low
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#define MAGIC_800_T1H 1350000 // 768ns actual; 412 low
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#pragma GCC push_options
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#pragma GCC optimize ("Os")
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void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout, uint8_t *pixels,
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uint32_t numBytes) {
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uint8_t *p = pixels, *end = p + numBytes, pix = *p++, mask = 0x80;
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uint32_t start = 0;
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uint32_t cyc = 0;
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// assumes 800_000Hz frequency
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// Theoretical values here are 800_000 -> 1.25us, 2500000->0.4us, 1250000->0.8us
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// TODO: try to get dynamic weighting working again
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uint32_t sys_freq = HAL_RCC_GetSysClockFreq();
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uint32_t interval = sys_freq / MAGIC_800_INT;
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uint32_t t0 = (sys_freq / MAGIC_800_T0H);
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uint32_t t1 = (sys_freq / MAGIC_800_T1H);
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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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GPIO_TypeDef *p_port = pin_port(digitalinout->pin->port);
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uint32_t p_mask = pin_mask(digitalinout->pin->number);
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__disable_irq();
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// Enable DWT in debug core. Usable when interrupts disabled, as opposed to Systick->VAL
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CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
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DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
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DWT->CYCCNT = 0;
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for (;;) {
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cyc = (pix & mask) ? t1 : t0;
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start = DWT->CYCCNT;
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LL_GPIO_SetOutputPin(p_port, p_mask);
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while ((DWT->CYCCNT - start) < cyc) {
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;
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}
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LL_GPIO_ResetOutputPin(p_port, p_mask);
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while ((DWT->CYCCNT - start) < interval) {
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;
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}
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if (!(mask >>= 1)) {
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if (p >= end) {
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break;
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}
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pix = *p++;
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mask = 0x80;
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}
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}
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// Enable interrupts again
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__enable_irq();
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// Update the next start.
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next_start_raw_ticks = port_get_raw_ticks(NULL) + 4;
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}
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#pragma GCC pop_options
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