Implement Neopixel write, add defaults to f405

ports/stm32f4/boards/feather_stm32f405_express/mpconfigboard.h

@@ -35,6 +35,8 @@
 #define AUTORESET_DELAY_MS 500
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000)
 
+#define MICROPY_HW_NEOPIXEL &pin_PC00
+
 // On-board flash
 #define SPI_FLASH_MOSI_PIN          &pin_PB05
 #define SPI_FLASH_MISO_PIN          &pin_PB04

ports/stm32f4/boards/feather_stm32f405_express/pins.c

@@ -26,6 +26,7 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_TX), MP_ROM_PTR(&pin_PB10) },
     { MP_ROM_QSTR(MP_QSTR_RX), MP_ROM_PTR(&pin_PB11) },
 
+    { MP_ROM_QSTR(MP_QSTR_NEOPIXEL), MP_ROM_PTR(&pin_PC00) },
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&board_i2c_obj) },
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&board_spi_obj) },
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&board_uart_obj) },

ports/stm32f4/common-hal/microcontroller/Pin.h

@@ -31,6 +31,10 @@
 
 #include "peripherals/stm32f4/pins.h"
 
+#ifdef MICROPY_HW_NEOPIXEL
+extern bool neopixel_in_use;
+#endif
+
 void reset_all_pins(void);
 // reset_pin_number takes the pin number instead of the pointer so that objects don't
 // need to store a full pointer.

ports/stm32f4/common-hal/neopixel_write/__init__.c

@@ -0,0 +1,89 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Lucian Copeland for Adafruit Industries
+ *
+ * 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.
+ */
+
+#include "py/mphal.h"
+#include "shared-bindings/neopixel_write/__init__.h"
+
+#include "tick.h"
+#include "common-hal/microcontroller/Pin.h"
+#include "stm32f4xx_hal.h"
+#include "stm32f4xx_ll_gpio.h"
+
+uint64_t next_start_tick_ms = 0;
+uint32_t next_start_tick_us = 1000;
+
+void common_hal_neopixel_write (const digitalio_digitalinout_obj_t* digitalinout, uint8_t *pixels, 
+                                uint32_t numBytes) {
+    uint8_t *p = pixels, *end = p + numBytes, pix = *p++, mask = 0x80;
+    uint32_t start = 0;
+    uint32_t cyc = 0;
+
+    //assumes 800_000Hz frequency
+    uint32_t sys_freq = HAL_RCC_GetSysClockFreq();
+    uint32_t interval = sys_freq/800000;             // cycles per interval (1.25 us). 210@168MHz
+    uint32_t t0 = interval - (sys_freq/2500000);     // 0.4 us
+    uint32_t t1 = interval - (sys_freq/1250000);     // 0.8 us
+
+    // This must be called while interrupts are on in case we're waiting for a
+    // future ms tick.
+    wait_until(next_start_tick_ms, next_start_tick_us);
+
+    __disable_irq();
+    // Enable DWT in debug core. Useable when interrupts disabled, as opposed to Systick->VAL
+    //ITM->LAR = 0xC5ACCE55; //is this required?
+    CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+    DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
+    DWT->CYCCNT = 0;
+
+    GPIO_TypeDef * p_port = pin_port(digitalinout->pin->port);
+    uint32_t p_mask = pin_mask(digitalinout->pin->number);
+
+    for(;;) {
+        LL_GPIO_SetOutputPin(p_port, p_mask);
+        cyc = (pix & mask) ? t1 : t0;
+        start = DWT->CYCCNT;
+        while(DWT->CYCCNT - start < cyc);
+        LL_GPIO_ResetOutputPin(p_port, p_mask);
+        if(!(mask >>= 1)) { //max has shifted all the way
+            if(p >= end) break;
+            pix       = *p++;
+            mask = 0x80;
+        }
+        while(DWT->CYCCNT - start < interval); //wait for interval to finish
+    }
+
+    // Enable interrupts again
+    __enable_irq();
+
+    // Update the next start.
+    current_tick(&next_start_tick_ms, &next_start_tick_us);
+    if (next_start_tick_us < 100) {
+        next_start_tick_ms += 1;
+        next_start_tick_us = 100 - next_start_tick_us;
+    } else {
+        next_start_tick_us -= 100;
+    }
+}

ports/stm32f4/mpconfigport.mk

@@ -26,6 +26,7 @@ CIRCUITPY_STORAGE = 1
 CIRCUITPY_RANDOM = 1
 CIRCUITPY_USB_HID = 1
 CIRCUITPY_USB_MIDI = 1
+CIRCUITPY_NEOPIXEL_WRITE = 1
 
 #ifeq ($(MCU_SUB_VARIANT), stm32f412zx)
 #endif