Use the entire 128-bit CPU serial number

firmware/Makefile

@@ -22,7 +22,6 @@ OPTIONS = -DF_CPU=48000000
 # Sources
 C_FILES = \
 	mk20dx128.c \
-	nonstd.c \
 	pins_teensy.c \
 	usb_desc.c \
 	usb_dev.c \

firmware/nonstd.c

-/* Teensyduino Core Library
- * http://www.pjrc.com/teensy/
- * Copyright (c) 2013 PJRC.COM, LLC.
- *
- * 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:
- *
- * 1. The above copyright notice and this permission notice shall be 
- * included in all copies or substantial portions of the Software.
- *
- * 2. If the Software is incorporated into a build system that allows 
- * selection among a list of target devices, then similar target
- * devices manufactured by PJRC.COM must be included in the list of
- * target devices and selectable in the same manner.
- *
- * 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 <string.h>
-#include <stdio.h>
-
-size_t strlen(const char *s)
-{
-    size_t n=0;
-
-    while (*s++) n++;
-    return n;
-}
-
-char * ultoa(unsigned long val, char *buf, int radix)   
-{
-    unsigned digit;
-    int i=0, j;
-    char t;
-
-    while (1) {
-        digit = val % radix;
-        buf[i] = ((digit < 10) ? '0' + digit : 'A' + digit - 10);
-        val /= radix;
-        if (val == 0) break;
-        i++;
-    }
-    buf[i + 1] = 0;
-    for (j=0; j < i; j++, i--) {
-        t = buf[j];
-        buf[j] = buf[i];
-        buf[i] = t;
-    }
-    return buf;
-}
-
-char * ltoa(long val, char *buf, int radix)
-{
-    if (val >= 0) {
-        return ultoa(val, buf, radix);
-    } else {
-        buf[0] = '-';
-        ultoa(-val, buf + 1, radix);
-        return buf;
-    }
-}
-

firmware/usb_desc.c

@@ -174,32 +174,33 @@ struct usb_string_descriptor_struct usb_string_product_name_default = {
         3,
         PRODUCT_NAME
 };
+
+// 32-digit hex string, corresponding to the MK20DX128's built-in unique 128-bit ID.
 struct usb_string_descriptor_struct usb_string_serial_number_default = {
-        12,
+        2 + 32 * 2,
         3,
-        {0,0,0,0,0,0,0,0,0,0}
+        {0,0,0,0,0,0,0,0,
+         0,0,0,0,0,0,0,0,
+         0,0,0,0,0,0,0,0,
+         0,0,0,0,0,0,0,0}
 };
 
+static void toHexWide(uint32_t value, uint16_t *buffer)
+{
+    static const uint8_t digits[] = "0123456789ABCDEF";
+    unsigned i;
+    for (i = 0; i < 8; i++) {
+        buffer[i] = digits[value >> 28];
+        value <<= 4;
+    }
+}
+
 void usb_init_serialnumber(void)
 {
-        char buf[11];
-        uint32_t i, num;
-
-        __disable_irq();
-        FTFL_FSTAT = FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL;
-        FTFL_FCCOB0 = 0x41;
-        FTFL_FCCOB1 = 15;
-        FTFL_FSTAT = FTFL_FSTAT_CCIF;
-        while (!(FTFL_FSTAT & FTFL_FSTAT_CCIF)) ; // wait
-        num = *(uint32_t *)&FTFL_FCCOB7;
-        __enable_irq();
-        ultoa(num, buf, 10);
-        for (i=0; i<10; i++) {
-                char c = buf[i];
-                if (!c) break;
-                usb_string_serial_number_default.wString[i] = c;
-        }
-        usb_string_serial_number_default.bLength = i * 2 + 2;
+    toHexWide(SIM_UIDH,  usb_string_serial_number_default.wString + 8*0);
+    toHexWide(SIM_UIDMH, usb_string_serial_number_default.wString + 8*1);
+    toHexWide(SIM_UIDML, usb_string_serial_number_default.wString + 8*2);
+    toHexWide(SIM_UIDL,  usb_string_serial_number_default.wString + 8*3);
 }