pbio/drv/usb_nxt: Implement serial number descriptor.

The browser needs this to automatically reconnect to a known device.

Author: laurensvalk

lib/pbio/drv/usb/usb_nxt.c

@@ -99,6 +99,7 @@ enum {
     STRING_DESC_LANGID,
     STRING_DESC_MFG,
     STRING_DESC_PRODUCT,
+    STRING_DESC_SERIAL,
 };
 
 /* The following definitions are 'raw' USB setup packets. They are all
@@ -127,7 +128,7 @@ static const pbdrv_usb_dev_desc_t pbdrv_usb_nxt_device_descriptor = {
     .bcdDevice = 0x0200,    /* Product revision: 2.0.0. */
     .iManufacturer = STRING_DESC_MFG,
     .iProduct = STRING_DESC_PRODUCT,
-    .iSerialNumber = 0,     // TODO: implement a serial number
+    .iSerialNumber = STRING_DESC_SERIAL,
     .bNumConfigurations = 1,
 };
 
@@ -188,6 +189,15 @@ static const pbdrv_usb_nxt_conf_t pbdrv_usb_nxt_full_config = {
     },
 };
 
+// Serial number descriptor
+typedef struct PBDRV_PACKED {
+    uint8_t bLength;
+    uint8_t bDescriptorType;
+    uint16_t wString[6 * 3]; // 6 hex bytes separated by ':' and ending in 0.
+} pbdrv_usb_serial_number_desc_t;
+
+static pbdrv_usb_serial_number_desc_t pbdrv_usb_str_desc_serial;
+
 typedef enum {
     USB_UNINITIALIZED,
     USB_READY,
@@ -441,6 +451,10 @@ static void pbdrv_usb_handle_std_request(pbdrv_usb_nxt_setup_packet_t *packet) {
                             desc = &pbdrv_usb_str_desc_prod;
                             size = sizeof(pbdrv_usb_str_desc_prod.s);
                             break;
+                        case STRING_DESC_SERIAL:
+                            desc = &pbdrv_usb_str_desc_serial;
+                            size = sizeof(pbdrv_usb_str_desc_serial);
+                            break;
                     }
 
                     if (desc) {
@@ -770,6 +784,14 @@ void pbdrv_usb_nxt_deinit(void) {
 }
 
 void pbdrv_usb_init_device(void) {
+
+    extern char bluetooth_address_string[PBIO_ARRAY_SIZE(pbdrv_usb_str_desc_serial.wString)];
+    for (uint8_t i = 0; i < PBIO_ARRAY_SIZE(pbdrv_usb_str_desc_serial.wString); i++) {
+        pbdrv_usb_str_desc_serial.wString[i] = bluetooth_address_string[i];
+    }
+    pbdrv_usb_str_desc_serial.bLength = PBIO_ARRAY_SIZE(pbdrv_usb_str_desc_serial.wString) * 2;
+    pbdrv_usb_str_desc_serial.bDescriptorType = USB_DESC_TYPE_STR,
+
     pbdrv_usb_nxt_deinit();
     memset((void *)&pbdrv_usb_nxt_state, 0, sizeof(pbdrv_usb_nxt_state));
 

lib/pbio/platform/nxt/platform.c

@@ -5,6 +5,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 
 #include <pbdrv/config.h>
@@ -111,31 +112,23 @@ const pbdrv_ioport_platform_data_t pbdrv_ioport_platform_data[PBDRV_CONFIG_IOPOR
     },
 };
 
-const char *pin = "1234";
+char bluetooth_address_string[6 * 3]; // 6 hex bytes separated by ':' and ending in 0.
 
 static void legacy_bluetooth_init_blocking(void) {
     nx_bt_init();
 
-    char *name = "Pybricks NXT";
-    nx_bt_set_friendly_name(name);
+    nx_bt_set_friendly_name("Pybricks NXT");
 
-    nx_display_string("Bluetooth name:\n");
-    nx_display_string(name);
-    nx_display_string("\n");
     uint8_t local_addr[7];
     if (nx_bt_get_local_addr(local_addr)) {
-        for (int i = 0; i < 6; i++) {
-            nx_display_hex(local_addr[i]);
-            nx_display_string(i < 5 ? ":": "\n");
-        }
+        snprintf(bluetooth_address_string, sizeof(bluetooth_address_string),
+            "%02X:%02X:%02X:%02X:%02X:%02X",
+            local_addr[0], local_addr[1], local_addr[2],
+            local_addr[3], local_addr[4], local_addr[5]);
     }
-    nx_display_string("Pin: ");
-    nx_display_string(pin);
-    nx_display_string("\n\nConnect to me as BT serial port.\n");
 
-    nx_bt_set_discoverable(true);
-
-    nx_bt_open_port();
+    nx_display_string(bluetooth_address_string);
+    nx_display_string("\n");
 }
 
 // REVISIT: This process waits for the user to connect to the NXT brick with
@@ -155,7 +148,7 @@ static pbio_error_t legacy_bluetooth_connect_process_thread(pbio_os_state_t *sta
     while (!nx_bt_stream_opened()) {
 
         if (nx_bt_has_dev_waiting_for_pin()) {
-            nx_bt_send_pin((char *)pin);
+            nx_bt_send_pin("1234");
             nx_display_string("Please enter pin.\n");
         } else if (nx_bt_connection_pending()) {
             nx_display_string("Connecting ...\n");