Add support for ESP32 boards using the native TWAI (CAN) driver.

Changes:
- Add ODriveESP32TWAI.hpp interface that calls twai_transmit/twai_receive directly
- Add IS_ESP32_TWAI option to SineWaveCAN example
- Add esp32 PlatformIO target

Author: solomondg

examples/SineWaveCAN/SineWaveCAN.ino

@@ -21,11 +21,12 @@
 // #define IS_ARDUINO_BUILTIN // Arduino boards with built-in CAN interface (e.g. Arduino Uno R4 Minima)
 // #define IS_MCP2515 // Any board with external MCP2515 based extension module. See below to configure the module.
 // #define IS_STM32_BUILTIN // STM32 boards with built-in CAN interface (e.g. STM32F4 Discovery).
+// #define IS_ESP32_TWAI // ESP32 boards with built-in TWAI (CAN) interface. Directly uses the ESP-IDF TWAI driver.
 
 
 /* Board-specific includes ---------------------------------------------------*/
 
-#if defined(IS_TEENSY_BUILTIN) + defined(IS_ARDUINO_BUILTIN) + defined(IS_MCP2515) + defined(IS_STM32_BUILTIN) != 1
+#if defined(IS_TEENSY_BUILTIN) + defined(IS_ARDUINO_BUILTIN) + defined(IS_MCP2515) + defined(IS_STM32_BUILTIN) + defined(IS_ESP32_TWAI) != 1
 #warning "Select exactly one hardware option at the top of this file."
 
 #if CAN_HOWMANY > 0 || CANFD_HOWMANY > 0
@@ -65,6 +66,12 @@ struct ODriveStatus; // hack to prevent teensy compile error
 #include "ODriveSTM32CAN.hpp"
 #endif // IS_STM32_BUILTIN
 
+#ifdef IS_ESP32_TWAI
+// See https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/twai.html
+#include "driver/twai.h"
+#include "ODriveESP32TWAI.hpp"
+#endif // IS_ESP32_TWAI
+
 
 
 /* Board-specific settings ---------------------------------------------------*/
@@ -160,6 +167,54 @@ bool setupCan() {
 #endif // IS_STM32_BUILTIN
 
 
+/* ESP32 boards with built-in TWAI (CAN) */
+
+#ifdef IS_ESP32_TWAI
+
+// Pins used to connect to CAN bus transceiver
+#define ESP32_TWAI_TX_PIN 5
+#define ESP32_TWAI_RX_PIN 4
+
+ESP32TWAIIntf can_intf;
+
+bool setupCan() {
+    twai_general_config_t g_config = TWAI_GENERAL_CONFIG_DEFAULT(
+        (gpio_num_t)ESP32_TWAI_TX_PIN,
+        (gpio_num_t)ESP32_TWAI_RX_PIN,
+        TWAI_MODE_NORMAL
+    );
+
+    twai_timing_config_t t_config;
+    switch (CAN_BAUDRATE) {
+        case 1000000: t_config = TWAI_TIMING_CONFIG_1MBITS(); break;
+        case 800000:  t_config = TWAI_TIMING_CONFIG_800KBITS(); break;
+        case 500000:  t_config = TWAI_TIMING_CONFIG_500KBITS(); break;
+        case 250000:  t_config = TWAI_TIMING_CONFIG_250KBITS(); break;
+        case 125000:  t_config = TWAI_TIMING_CONFIG_125KBITS(); break;
+        case 100000:  t_config = TWAI_TIMING_CONFIG_100KBITS(); break;
+        case 50000:   t_config = TWAI_TIMING_CONFIG_50KBITS(); break;
+        case 25000:   t_config = TWAI_TIMING_CONFIG_25KBITS(); break;
+        default:      t_config = TWAI_TIMING_CONFIG_250KBITS(); break;
+    }
+
+    twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();
+
+    if (twai_driver_install(&g_config, &t_config, &f_config) != ESP_OK) {
+        return false;
+    }
+
+    if (twai_start() != ESP_OK) {
+        twai_driver_uninstall();
+        return false;
+    }
+
+    can_intf.initialized = true;
+    return true;
+}
+
+#endif // IS_ESP32_TWAI
+
+
 /* Example sketch ------------------------------------------------------------*/
 
 // Instantiate ODrive objects

platformio.ini

@@ -46,4 +46,10 @@ build_flags =
   ; See https://github.com/pazi88/STM32_CAN
   -DHAL_CAN_MODULE_ENABLED
 lib_deps =
-    https://github.com/pazi88/STM32_CAN.git#1.2.0
+    https://github.com/pazi88/STM32_CAN.git#1.2.0
+
+[env:esp32]
+platform = espressif32
+board = esp32dev
+framework = arduino
+build_flags = -DIS_ESP32_TWAI

src/ODriveESP32TWAI.hpp

@@ -0,0 +1,66 @@
+// CAN glue layer for ESP32 platforms using the native TWAI driver.
+// See ODriveHardwareCAN.hpp for documentation.
+
+#pragma once
+
+#include "ODriveCAN.h"
+#include "driver/twai.h"
+
+// Simple struct to hold TWAI interface state. Unlike other platforms, ESP32's
+// TWAI driver uses global functions rather than a class instance.
+struct ESP32TWAIIntf {
+    bool initialized = false;
+};
+
+struct CanMsg {
+    uint32_t id;
+    uint8_t len;
+    uint8_t buffer[8];
+};
+
+// Must be defined by the application
+void onCanMessage(const CanMsg& msg);
+
+static bool sendMsg(ESP32TWAIIntf& intf, uint32_t id, uint8_t length, const uint8_t* data) {
+    if (!intf.initialized) {
+        return false;
+    }
+
+    twai_message_t tx_msg = {};
+    tx_msg.identifier = id;
+    tx_msg.data_length_code = length;
+    tx_msg.extd = (id > 0x7FF) ? 1 : 0;
+    tx_msg.rtr = (data == nullptr) ? 1 : 0;
+
+    if (data) {
+        for (int i = 0; i < length; ++i) {
+            tx_msg.data[i] = data[i];
+        }
+    }
+
+    return twai_transmit(&tx_msg, pdMS_TO_TICKS(100)) == ESP_OK;
+}
+
+static void onReceive(const CanMsg& msg, ODriveCAN& odrive) {
+    odrive.onReceive(msg.id, msg.len, msg.buffer);
+}
+
+static void pumpEvents(ESP32TWAIIntf& intf, int max_events = 100) {
+    if (!intf.initialized) {
+        return;
+    }
+
+    // max_events prevents an infinite loop if messages come at a high rate
+    twai_message_t rx_msg;
+    while (twai_receive(&rx_msg, 0) == ESP_OK && max_events--) {
+        CanMsg msg;
+        msg.id = rx_msg.identifier;
+        msg.len = rx_msg.data_length_code;
+        for (int i = 0; i < rx_msg.data_length_code && i < 8; ++i) {
+            msg.buffer[i] = rx_msg.data[i];
+        }
+        onCanMessage(msg);
+    }
+}
+
+CREATE_CAN_INTF_WRAPPER(ESP32TWAIIntf)