add USB functionality

Makefile

@@ -5,6 +5,9 @@ GOSSAMER_PATH=gossamer
 # or omit it and provide it on the command line (make BOARD=foo).
 BOARD=sensorwatch_green
 
+# TinyUSB configuration: we want one CDC interface.
+TINYUSB_CDC=1
+
 # Leave this line here.
 include $(GOSSAMER_PATH)/make.mk
 
@@ -15,8 +18,12 @@ SRCS += \
   ./watch-library/hardware/watch/watch_buzzer.c \
   ./watch-library/hardware/watch/watch_led.c \
   ./watch-library/hardware/watch/watch_private.c \
+  ./watch-library/hardware/watch/watch_usb_descriptors.c \
+  ./watch-library/hardware/watch/watch_usb_cdc.c \
 
 INCLUDES += \
+  -I./tinyusb/src \
+  -I./watch-library/hardware/watch \
   -I./watch-library/shared/watch \
 
 # Finally, leave this line at the bottom of the file.

app.c

@@ -1,9 +1,50 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2021-2024 Joey Castillo
+ *
+ * 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 "app.h"
 #include "delay.h"
 #include "watch.h"
 #include "watch_private.h"
+#include "usb.h"
+#include "tusb.h"
+#include "watch_usb_cdc.h"
+
+void yield(void) {
+    tud_task();
+    cdc_task();
+}
 
 void app_init(void) {
+    // check if we are plugged into USB power.
+    HAL_GPIO_VBUS_DET_in();
+    HAL_GPIO_VBUS_DET_pulldown();
+    if (HAL_GPIO_VBUS_DET_read()){
+        /// if so, enable USB functionality.
+        _watch_enable_usb();
+    }
+    HAL_GPIO_VBUS_DET_off();
+
     _watch_init();
 }
 
@@ -17,5 +58,9 @@ bool app_loop(void) {
     watch_set_led_off();
     delay_ms(500);
 
+    if (usb_is_enabled()) {
+        yield();
+    }
+
     return false;
 }

watch-library/hardware/watch/watch_private.c

@@ -25,6 +25,7 @@
 #include "watch_private.h"
 #include "tcc.h"
 #include "tc.h"
+#include "usb.h"
 
 void _watch_init(void) {
     // disable debugger hot-plugging
@@ -197,3 +198,8 @@ void _watch_disable_tcc(void) {
 #endif
     tcc_disable(0);
 }
+
+void _watch_enable_usb(void) {
+    usb_init();
+    usb_enable();
+}

watch-library/hardware/watch/watch_usb_cdc.c

@@ -0,0 +1,157 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 Joey Castillo
+ * Copyright (c) 2023 Edward Shin
+ *
+ * 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 <stddef.h>
+#include "watch_usb_cdc.h"
+#include "tusb.h"
+
+/*
+ * Implement a circular buffer for the USB CDC Serial read buffer.
+ * The size of the buffer must be a power of two for this circular buffer
+ * implementation to work.
+ */
+
+// Size of the circular buffer. Must be a power of two.
+#define CDC_WRITE_BUF_SZ  (1024)
+// Macro function to perform modular arithmetic on an index.
+// eg. (63 + 2) & (64 - 1) -> 1
+#define CDC_WRITE_BUF_IDX(x)  ((x) & (CDC_WRITE_BUF_SZ - 1))
+static char s_write_buf[CDC_WRITE_BUF_SZ] = {0};
+static size_t s_write_buf_pos = 0;
+static size_t s_write_buf_len = 0;
+
+#define CDC_READ_BUF_SZ  (256)
+#define CDC_READ_BUF_IDX(x)  ((x) & (CDC_READ_BUF_SZ - 1))
+static char s_read_buf[CDC_READ_BUF_SZ] = {0};
+static size_t s_read_buf_pos = 0;
+static size_t s_read_buf_len = 0;
+
+// Mask TC1 interrupts, preventing calls to cdc_task()
+static inline void prv_critical_section_enter(void) {
+    NVIC_DisableIRQ(TC1_IRQn);
+}
+
+// Unmask TC1 interrupts, allowing calls to cdc_task()
+static inline void prv_critical_section_exit(void) {
+    NVIC_EnableIRQ(TC1_IRQn);
+}
+
+int _write(int file, char *ptr, int len) {
+    (void) file;
+
+    if (ptr == NULL || len <= 0) {
+        return -1;
+    }
+
+    int bytes_written = 0;
+
+    prv_critical_section_enter();
+
+    for (int i = 0; i < len; i++) {
+        s_write_buf[s_write_buf_pos] = ptr[i];
+        s_write_buf_pos = CDC_WRITE_BUF_IDX(s_write_buf_pos + 1);
+        if (s_write_buf_len < CDC_WRITE_BUF_SZ) {
+            s_write_buf_len++;
+        }
+        bytes_written++;
+    }
+
+    prv_critical_section_exit();
+
+    return bytes_written;
+}
+
+int _read(int file, char *ptr, int len) {
+    (void) file;
+
+    prv_critical_section_enter();
+
+    if (ptr == NULL || len <= 0 || s_read_buf_len == 0) {
+        prv_critical_section_exit();
+        return -1;
+    }
+
+    // Clamp to the length of the read buffer
+    if ((size_t) len > s_read_buf_len) {
+        len = s_read_buf_len;
+    }
+
+    // Calculate the start of the circular buffer, and iterate from there
+    const size_t start_pos = CDC_READ_BUF_IDX(s_read_buf_pos - len);
+    for (size_t i = 0; i < (size_t) len; i++) {
+        const size_t idx = CDC_READ_BUF_IDX(start_pos + i);
+        ptr[i] = s_read_buf[idx];
+        s_read_buf[idx] = 0;
+    }
+
+    // Update circular buffer position and length
+    s_read_buf_len -= len;
+    s_read_buf_pos = CDC_READ_BUF_IDX(s_read_buf_pos - len);
+
+    prv_critical_section_exit();
+
+    return len;
+}
+
+static void prv_handle_reads(void) {
+    while (tud_cdc_available()) {
+        int c = tud_cdc_read_char();
+        if (c < 0) {
+            continue;
+        }
+        s_read_buf[s_read_buf_pos] = c;
+        s_read_buf_pos = CDC_READ_BUF_IDX(s_read_buf_pos + 1);
+        if (s_read_buf_len < CDC_READ_BUF_SZ) {
+            s_read_buf_len++;
+        }
+    }
+}
+
+static void prv_handle_writes(void) {
+    if (s_write_buf_len > 0) {
+        const size_t start_pos =
+            CDC_WRITE_BUF_IDX(s_write_buf_pos - s_write_buf_len);
+        for (size_t i = 0; i < (size_t) s_write_buf_len; i++) {
+            const size_t idx = CDC_WRITE_BUF_IDX(start_pos + i);
+            if (tud_cdc_available() > 0) {
+                // If we receive data while doing a large write, we need to
+                // fully service it before continuing to write, or the
+                // stack will crash.
+                prv_handle_reads();
+            }
+            if (tud_cdc_write_available()) {
+                tud_cdc_write(&s_write_buf[idx], 1);
+            }
+            s_write_buf[idx] = 0;
+            s_write_buf_len--;
+        }
+        tud_cdc_write_flush();
+    }
+}
+
+void cdc_task(void) {
+    prv_handle_reads();
+    prv_handle_writes();
+}

watch-library/hardware/watch/watch_usb_cdc.h

@@ -0,0 +1,33 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 Joey Castillo
+ * Copyright (c) 2023 Edward Shin
+ *
+ * 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.
+ */
+
+#ifndef _WATCH_PRIVATE_CDC_H_INCLUDED
+#define _WATCH_PRIVATE_CDC_H_INCLUDED
+
+int _write(int file, char *ptr, int len);
+int _read(int file, char *ptr, int len);
+void cdc_task(void);
+
+#endif

watch-library/hardware/watch/watch_usb_descriptors.c

@@ -0,0 +1,155 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ *
+ * 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 "tusb.h"
+
+//--------------------------------------------------------------------+
+// Device Descriptors
+//--------------------------------------------------------------------+
+tusb_desc_device_t const desc_device = {
+    .bLength            = sizeof(tusb_desc_device_t),
+    .bDescriptorType    = TUSB_DESC_DEVICE,
+    .bcdUSB             = 0x0200,
+
+    // Use Interface Association Descriptor (IAD) for CDC
+    // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
+    .bDeviceClass       = TUSB_CLASS_MISC,
+    .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
+    .bDeviceProtocol    = MISC_PROTOCOL_IAD,
+
+    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
+
+    .idVendor           = 0x1209,
+    .idProduct          = 0x2151,
+    .bcdDevice          = 0x0100,
+
+    .iManufacturer      = 0x01,
+    .iProduct           = 0x02,
+    .iSerialNumber      = 0x03,
+
+    .bNumConfigurations = 0x01
+};
+
+// Invoked when received GET DEVICE DESCRIPTOR
+// Application return pointer to descriptor
+uint8_t const * tud_descriptor_device_cb(void) {
+  return (uint8_t const *) &desc_device;
+}
+
+//--------------------------------------------------------------------+
+// Configuration Descriptor
+//--------------------------------------------------------------------+
+
+enum {
+    ITF_NUM_CDC = 0,
+    ITF_NUM_CDC_DATA,
+    ITF_NUM_TOTAL
+};
+
+#define CONFIG_TOTAL_LEN    (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN)
+
+#define EPNUM_CDC_NOTIF   0x81
+#define EPNUM_CDC_OUT     0x02
+#define EPNUM_CDC_IN      0x82
+
+
+uint8_t const desc_fs_configuration[] = {
+    // Config number, interface count, string index, total length, attribute, power in mA
+    TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, TUSB_DESC_CONFIG_ATT_REMOTE_WAKEUP, 100),
+
+    // Interface number, string index, EP notification address and size, EP data address (out, in) and size.
+    TUD_CDC_DESCRIPTOR(ITF_NUM_CDC, 4, EPNUM_CDC_NOTIF, 8, EPNUM_CDC_OUT, EPNUM_CDC_IN, 64),
+};
+
+// Invoked when received GET CONFIGURATION DESCRIPTOR
+// Application return pointer to descriptor
+// Descriptor contents must exist long enough for transfer to complete
+uint8_t const * tud_descriptor_configuration_cb(uint8_t index) {
+    (void) index; // for multiple configurations
+    return desc_fs_configuration;
+}
+
+//--------------------------------------------------------------------+
+// String Descriptors
+//--------------------------------------------------------------------+
+
+static char serialnum[32 * 2 + 1] = {'\0'}; // 2 chars per hexnumber + '\0'
+
+// array of pointer to string descriptors
+char const* string_desc_arr [] = {
+    (const char[]) { 0x09, 0x04 },  // 0: is supported language is English (0x0409)
+    "Oddly Specific Objects",       // 1: Manufacturer
+    "Sensor Watch",                 // 2: Product
+    serialnum,                      // 3: Serial number
+    "TinyUSB CDC",                  // 4: CDC Interface
+};
+
+static uint16_t _desc_str[32];
+static bool serial_number_written = false;
+
+// Invoked when received GET STRING DESCRIPTOR request
+// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
+uint16_t const* tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
+    (void) langid;
+    uint8_t chr_count;
+
+    if (!serial_number_written) {
+        // Generate serial number based on chip unique ID
+        uint32_t chipid[4];
+        chipid[0] = *((uint32_t *)0x0080A00C);
+        chipid[1] = *((uint32_t *)0x0080A040);
+        chipid[2] = *((uint32_t *)0x0080A044);
+        chipid[3] = *((uint32_t *)0x0080A048);
+
+        sprintf(serialnum, "%08lX%08lX%08lX%08lX", chipid[0], chipid[1], chipid[2], chipid[3]);
+        serial_number_written = true;
+    }
+
+    if (index == 0) {
+        memcpy(&_desc_str[1], string_desc_arr[0], 2);
+        chr_count = 1;
+    } else {
+        // Note: the 0xEE index string is a Microsoft OS 1.0 Descriptors.
+        // https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-defined-usb-descriptors
+
+        if ( !(index < sizeof(string_desc_arr)/sizeof(string_desc_arr[0])) ) return NULL;
+
+        const char* str = string_desc_arr[index];
+
+        // Cap at max char
+        chr_count = strlen(str);
+        if ( chr_count > 31 ) chr_count = 31;
+
+        // Convert ASCII string into UTF-16
+        for(uint8_t i=0; i<chr_count; i++) {
+            _desc_str[1+i] = str[i];
+        }
+    }
+
+    // first byte is length (including header), second byte is string type
+    _desc_str[0] = (TUSB_DESC_STRING << 8 ) | (2*chr_count + 2);
+
+    return _desc_str;
+}

watch-library/shared/watch/watch_private.h

@@ -38,4 +38,7 @@ void _watch_enable_tcc(void);
 /// Called by buzzer and LED teardown functions.
 void _watch_disable_tcc(void);
 
+/// Called by main.c if plugged in to USB. You should not call this from your app.
+void _watch_enable_usb(void);
+
 #endif