Change ESP32 espShow to use RMT peripheral

esp.c

@@ -0,0 +1,160 @@
+// Implements the RMT peripheral on Espressif SoCs
+// Copyright (c) 2020 Lucian Copeland for Adafruit Industries
+
+/* Uses code from Espressif RGB LED Strip demo and drivers
+ * Copyright 2015-2020 Espressif Systems (Shanghai) PTE LTD
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if defined(ESP32)
+
+#include <Arduino.h>
+#include "driver/rmt.h"
+
+// This code is adapted from the ESP-IDF v3.4 RMT "led_strip" example, altered
+// to work with the Arduino version of the ESP-IDF (3.2)
+
+#define WS2812_T0H_NS (400)
+#define WS2812_T0L_NS (850)
+#define WS2812_T1H_NS (800)
+#define WS2812_T1L_NS (450)
+
+#define WS2811_T0H_NS (500)
+#define WS2811_T0L_NS (2000)
+#define WS2811_T1H_NS (1200)
+#define WS2811_T1L_NS (1300)
+
+static uint32_t t0h_ticks = 0;
+static uint32_t t1h_ticks = 0;
+static uint32_t t0l_ticks = 0;
+static uint32_t t1l_ticks = 0;
+
+// Limit the number of RMT channels available for the Neopixels. Defaults to all
+// channels (8 on ESP32, 4 on ESP32-S2 and S3). Redefining this value will free
+// any channels with a higher number for other uses, such as IR send-and-recieve
+// libraries. Redefine as 1 to restrict Neopixels to only a single channel.
+#define ADAFRUIT_RMT_CHANNEL_MAX RMT_CHANNEL_MAX
+
+#define RMT_LL_HW_BASE  (&RMT)
+
+bool rmt_reserved_channels[ADAFRUIT_RMT_CHANNEL_MAX];
+
+static void IRAM_ATTR ws2812_rmt_adapter(const void *src, rmt_item32_t *dest, size_t src_size,
+        size_t wanted_num, size_t *translated_size, size_t *item_num)
+{
+    if (src == NULL || dest == NULL) {
+        *translated_size = 0;
+        *item_num = 0;
+        return;
+    }
+    const rmt_item32_t bit0 = {{{ t0h_ticks, 1, t0l_ticks, 0 }}}; //Logical 0
+    const rmt_item32_t bit1 = {{{ t1h_ticks, 1, t1l_ticks, 0 }}}; //Logical 1
+    size_t size = 0;
+    size_t num = 0;
+    uint8_t *psrc = (uint8_t *)src;
+    rmt_item32_t *pdest = dest;
+    while (size < src_size && num < wanted_num) {
+        for (int i = 0; i < 8; i++) {
+            // MSB first
+            if (*psrc & (1 << (7 - i))) {
+                pdest->val =  bit1.val;
+            } else {
+                pdest->val =  bit0.val;
+            }
+            num++;
+            pdest++;
+        }
+        size++;
+        psrc++;
+    }
+    *translated_size = size;
+    *item_num = num;
+}
+
+void espShow(uint8_t pin, uint8_t *pixels, uint32_t numBytes, boolean is800KHz) {
+    // Reserve channel
+    rmt_channel_t channel = ADAFRUIT_RMT_CHANNEL_MAX;
+    for (size_t i = 0; i < ADAFRUIT_RMT_CHANNEL_MAX; i++) {
+        if (!rmt_reserved_channels[i]) {
+            rmt_reserved_channels[i] = true;
+            channel = i;
+        }
+    }
+    if (channel == ADAFRUIT_RMT_CHANNEL_MAX) {
+        // Ran out of channels!
+        return;
+    }
+
+    // Match default TX config from ESP-IDF version 3.4
+    rmt_config_t config = {
+        .rmt_mode = RMT_MODE_TX,
+        .channel = channel,
+        .gpio_num = pin,
+        .clk_div = 2,
+        .mem_block_num = 1,
+        .tx_config = {
+            .carrier_freq_hz = 38000,
+            .carrier_level = RMT_CARRIER_LEVEL_HIGH,
+            .idle_level = RMT_IDLE_LEVEL_LOW,
+            .carrier_duty_percent = 33,
+            .carrier_en = false,
+            .loop_en = false,
+            .idle_output_en = true,
+        }
+    };
+    rmt_config(&config);
+    rmt_driver_install(config.channel, 0, 0);
+
+    // Convert NS timings to ticks
+    uint32_t counter_clk_hz = 0;
+
+    // this emulates the rmt_get_counter_clock() function from ESP-IDF 3.4
+    if (RMT_LL_HW_BASE->conf_ch[config.channel].conf1.ref_always_on == RMT_BASECLK_REF) {
+        uint32_t div_cnt = RMT_LL_HW_BASE->conf_ch[config.channel].conf0.div_cnt;
+        uint32_t div = div_cnt == 0 ? 256 : div_cnt;
+        counter_clk_hz = REF_CLK_FREQ / (div);
+    } else {
+        uint32_t div_cnt = RMT_LL_HW_BASE->conf_ch[config.channel].conf0.div_cnt;
+        uint32_t div = div_cnt == 0 ? 256 : div_cnt;
+        counter_clk_hz = APB_CLK_FREQ / (div);
+    }
+
+    // NS to tick converter
+    float ratio = (float)counter_clk_hz / 1e9;
+
+    if (is800KHz) {
+        t0h_ticks = (uint32_t)(ratio * WS2812_T0H_NS);
+        t0l_ticks = (uint32_t)(ratio * WS2812_T0L_NS);
+        t1h_ticks = (uint32_t)(ratio * WS2812_T1H_NS);
+        t1l_ticks = (uint32_t)(ratio * WS2812_T1L_NS);
+    } else {
+        t0h_ticks = (uint32_t)(ratio * WS2811_T0H_NS);
+        t0l_ticks = (uint32_t)(ratio * WS2811_T0L_NS);
+        t1h_ticks = (uint32_t)(ratio * WS2811_T1H_NS);
+        t1l_ticks = (uint32_t)(ratio * WS2811_T1L_NS);
+    }
+
+    // Initialize automatic timing translator
+    rmt_translator_init(config.channel, ws2812_rmt_adapter);
+
+    // Write and wait to finish
+    rmt_write_sample(config.channel, pixels, (size_t)numBytes, true);
+    rmt_wait_tx_done(config.channel, pdMS_TO_TICKS(100));
+
+    // Free channel again
+    rmt_driver_uninstall(config.channel);
+    rmt_reserved_channels[channel] = false;
+}
+
+#endif

esp8266.c

@@ -2,7 +2,7 @@
 // ESP8266 work for the NeoPixelBus library: github.com/Makuna/NeoPixelBus
 // Needs to be a separate .c file to enforce ICACHE_RAM_ATTR execution.
 
-#if defined(ESP8266) || defined(ESP32)
+#if defined(ESP8266)
 
 #include <Arduino.h>
 #ifdef ESP8266