teensy3/mk20dx128.c

   1 /* Teensyduino Core Library
   2  * http://www.pjrc.com/teensy/
   3  * Copyright (c) 2013 PJRC.COM, LLC.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining
   6  * a copy of this software and associated documentation files (the
   7  * "Software"), to deal in the Software without restriction, including
   8  * without limitation the rights to use, copy, modify, merge, publish,
   9  * distribute, sublicense, and/or sell copies of the Software, and to
  10  * permit persons to whom the Software is furnished to do so, subject to
  11  * the following conditions:
  12  *
  13  * 1. The above copyright notice and this permission notice shall be
  14  * included in all copies or substantial portions of the Software.
  15  *
  16  * 2. If the Software is incorporated into a build system that allows
  17  * selection among a list of target devices, then similar target
  18  * devices manufactured by PJRC.COM must be included in the list of
  19  * target devices and selectable in the same manner.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  25  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  26  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  27  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  28  * SOFTWARE.
  29  */
  30
  31 #include "mk20dx128.h"
  32
  33
  34 extern unsigned long _stext;
  35 extern unsigned long _etext;
  36 extern unsigned long _sdata;
  37 extern unsigned long _edata;
  38 extern unsigned long _sbss;
  39 extern unsigned long _ebss;
  40 extern unsigned long _estack;
  41 //extern void __init_array_start(void);
  42 //extern void __init_array_end(void);
  43 extern int main (void);
  44 void ResetHandler(void);
  45 void _init_Teensyduino_internal_(void);
  46 void __libc_init_array(void);
  47
  48
  49 void fault_isr(void)
  50 {
  51         while (1) {
  52                 // keep polling some communication while in fault
  53                 // mode, so we don't completely die.
  54                 if (SIM_SCGC4 & SIM_SCGC4_USBOTG) usb_isr();
  55                 if (SIM_SCGC4 & SIM_SCGC4_UART0) uart0_status_isr();
  56                 if (SIM_SCGC4 & SIM_SCGC4_UART1) uart1_status_isr();
  57                 if (SIM_SCGC4 & SIM_SCGC4_UART2) uart2_status_isr();
  58         }
  59 }
  60
  61 void unused_isr(void)
  62 {
  63         fault_isr();
  64 }
  65
  66 extern volatile uint32_t systick_millis_count;
  67 void systick_default_isr(void)
  68 {
  69         systick_millis_count++;
  70 }
  71
  72 void nmi_isr(void)              __attribute__ ((weak, alias("unused_isr")));
  73 void hard_fault_isr(void)       __attribute__ ((weak, alias("unused_isr")));
  74 void memmanage_fault_isr(void)  __attribute__ ((weak, alias("unused_isr")));
  75 void bus_fault_isr(void)        __attribute__ ((weak, alias("unused_isr")));
  76 void usage_fault_isr(void)      __attribute__ ((weak, alias("unused_isr")));
  77 void svcall_isr(void)           __attribute__ ((weak, alias("unused_isr")));
  78 void debugmonitor_isr(void)     __attribute__ ((weak, alias("unused_isr")));
  79 void pendablesrvreq_isr(void)   __attribute__ ((weak, alias("unused_isr")));
  80 void systick_isr(void)          __attribute__ ((weak, alias("systick_default_isr")));
  81
  82 void dma_ch0_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  83 void dma_ch1_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  84 void dma_ch2_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  85 void dma_ch3_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  86 void dma_ch4_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  87 void dma_ch5_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  88 void dma_ch6_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  89 void dma_ch7_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  90 void dma_ch8_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  91 void dma_ch9_isr(void)          __attribute__ ((weak, alias("unused_isr")));
  92 void dma_ch10_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  93 void dma_ch11_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  94 void dma_ch12_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  95 void dma_ch13_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  96 void dma_ch14_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  97 void dma_ch15_isr(void)         __attribute__ ((weak, alias("unused_isr")));
  98 void dma_error_isr(void)        __attribute__ ((weak, alias("unused_isr")));
  99 void mcm_isr(void)              __attribute__ ((weak, alias("unused_isr")));
 100 void flash_cmd_isr(void)        __attribute__ ((weak, alias("unused_isr")));
 101 void flash_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 102 void low_voltage_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 103 void wakeup_isr(void)           __attribute__ ((weak, alias("unused_isr")));
 104 void watchdog_isr(void)         __attribute__ ((weak, alias("unused_isr")));
 105 void i2c0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 106 void i2c1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 107 void i2c2_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 108 void spi0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 109 void spi1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 110 void spi2_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 111 void sdhc_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 112 void can0_message_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 113 void can0_bus_off_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 114 void can0_error_isr(void)       __attribute__ ((weak, alias("unused_isr")));
 115 void can0_tx_warn_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 116 void can0_rx_warn_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 117 void can0_wakeup_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 118 void i2s0_tx_isr(void)          __attribute__ ((weak, alias("unused_isr")));
 119 void i2s0_rx_isr(void)          __attribute__ ((weak, alias("unused_isr")));
 120 void uart0_lon_isr(void)        __attribute__ ((weak, alias("unused_isr")));
 121 void uart0_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 122 void uart0_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 123 void uart1_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 124 void uart1_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 125 void uart2_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 126 void uart2_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 127 void uart3_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 128 void uart3_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 129 void uart4_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 130 void uart4_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 131 void uart5_status_isr(void)     __attribute__ ((weak, alias("unused_isr")));
 132 void uart5_error_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 133 void adc0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 134 void adc1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 135 void cmp0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 136 void cmp1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 137 void cmp2_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 138 void ftm0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 139 void ftm1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 140 void ftm2_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 141 void ftm3_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 142 void cmt_isr(void)              __attribute__ ((weak, alias("unused_isr")));
 143 void rtc_alarm_isr(void)        __attribute__ ((weak, alias("unused_isr")));
 144 void rtc_seconds_isr(void)      __attribute__ ((weak, alias("unused_isr")));
 145 void pit0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 146 void pit1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 147 void pit2_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 148 void pit3_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 149 void pdb_isr(void)              __attribute__ ((weak, alias("unused_isr")));
 150 void usb_isr(void)              __attribute__ ((weak, alias("unused_isr")));
 151 void usb_charge_isr(void)       __attribute__ ((weak, alias("unused_isr")));
 152 void dac0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 153 void dac1_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 154 void tsi0_isr(void)             __attribute__ ((weak, alias("unused_isr")));
 155 void mcg_isr(void)              __attribute__ ((weak, alias("unused_isr")));
 156 void lptmr_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 157 void porta_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 158 void portb_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 159 void portc_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 160 void portd_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 161 void porte_isr(void)            __attribute__ ((weak, alias("unused_isr")));
 162 void software_isr(void)         __attribute__ ((weak, alias("unused_isr")));
 163
 164
 165 // TODO: create AVR-stype ISR() macro, with default linkage to undefined handler
 166 //
 167 __attribute__ ((section(".vectors"), used))
 168 void (* const gVectors[])(void) =
 169 {
 170         (void (*)(void))((unsigned long)&_estack),      //  0 ARM: Initial Stack Pointer
 171         ResetHandler,                                   //  1 ARM: Initial Program Counter
 172         nmi_isr,                                        //  2 ARM: Non-maskable Interrupt (NMI)
 173         hard_fault_isr,                                 //  3 ARM: Hard Fault
 174         memmanage_fault_isr,                            //  4 ARM: MemManage Fault
 175         bus_fault_isr,                                  //  5 ARM: Bus Fault
 176         usage_fault_isr,                                //  6 ARM: Usage Fault
 177         fault_isr,                                      //  7 --
 178         fault_isr,                                      //  8 --
 179         fault_isr,                                      //  9 --
 180         fault_isr,                                      // 10 --
 181         svcall_isr,                                     // 11 ARM: Supervisor call (SVCall)
 182         debugmonitor_isr,                               // 12 ARM: Debug Monitor
 183         fault_isr,                                      // 13 --
 184         pendablesrvreq_isr,                             // 14 ARM: Pendable req serv(PendableSrvReq)
 185         systick_isr,                                    // 15 ARM: System tick timer (SysTick)
 186 #if defined(__MK20DX128__)
 187         dma_ch0_isr,                                    // 16 DMA channel 0 transfer complete
 188         dma_ch1_isr,                                    // 17 DMA channel 1 transfer complete
 189         dma_ch2_isr,                                    // 18 DMA channel 2 transfer complete
 190         dma_ch3_isr,                                    // 19 DMA channel 3 transfer complete
 191         dma_error_isr,                                  // 20 DMA error interrupt channel
 192         unused_isr,                                     // 21 DMA --
 193         flash_cmd_isr,                                  // 22 Flash Memory Command complete
 194         flash_error_isr,                                // 23 Flash Read collision
 195         low_voltage_isr,                                // 24 Low-voltage detect/warning
 196         wakeup_isr,                                     // 25 Low Leakage Wakeup
 197         watchdog_isr,                                   // 26 Both EWM and WDOG interrupt
 198         i2c0_isr,                                       // 27 I2C0
 199         spi0_isr,                                       // 28 SPI0
 200         i2s0_tx_isr,                                    // 29 I2S0 Transmit
 201         i2s0_rx_isr,                                    // 30 I2S0 Receive
 202         uart0_lon_isr,                                  // 31 UART0 CEA709.1-B (LON) status
 203         uart0_status_isr,                               // 32 UART0 status
 204         uart0_error_isr,                                // 33 UART0 error
 205         uart1_status_isr,                               // 34 UART1 status
 206         uart1_error_isr,                                // 35 UART1 error
 207         uart2_status_isr,                               // 36 UART2 status
 208         uart2_error_isr,                                // 37 UART2 error
 209         adc0_isr,                                       // 38 ADC0
 210         cmp0_isr,                                       // 39 CMP0
 211         cmp1_isr,                                       // 40 CMP1
 212         ftm0_isr,                                       // 41 FTM0
 213         ftm1_isr,                                       // 42 FTM1
 214         cmt_isr,                                        // 43 CMT
 215         rtc_alarm_isr,                                  // 44 RTC Alarm interrupt
 216         rtc_seconds_isr,                                // 45 RTC Seconds interrupt
 217         pit0_isr,                                       // 46 PIT Channel 0
 218         pit1_isr,                                       // 47 PIT Channel 1
 219         pit2_isr,                                       // 48 PIT Channel 2
 220         pit3_isr,                                       // 49 PIT Channel 3
 221         pdb_isr,                                        // 50 PDB Programmable Delay Block
 222         usb_isr,                                        // 51 USB OTG
 223         usb_charge_isr,                                 // 52 USB Charger Detect
 224         tsi0_isr,                                       // 53 TSI0
 225         mcg_isr,                                        // 54 MCG
 226         lptmr_isr,                                      // 55 Low Power Timer
 227         porta_isr,                                      // 56 Pin detect (Port A)
 228         portb_isr,                                      // 57 Pin detect (Port B)
 229         portc_isr,                                      // 58 Pin detect (Port C)
 230         portd_isr,                                      // 59 Pin detect (Port D)
 231         porte_isr,                                      // 60 Pin detect (Port E)
 232         software_isr,                                   // 61 Software interrupt
 233 #elif defined(__MK20DX256__)
 234         dma_ch0_isr,                                    // 16 DMA channel 0 transfer complete
 235         dma_ch1_isr,                                    // 17 DMA channel 1 transfer complete
 236         dma_ch2_isr,                                    // 18 DMA channel 2 transfer complete
 237         dma_ch3_isr,                                    // 19 DMA channel 3 transfer complete
 238         dma_ch4_isr,                                    // 20 DMA channel 4 transfer complete
 239         dma_ch5_isr,                                    // 21 DMA channel 5 transfer complete
 240         dma_ch6_isr,                                    // 22 DMA channel 6 transfer complete
 241         dma_ch7_isr,                                    // 23 DMA channel 7 transfer complete
 242         dma_ch8_isr,                                    // 24 DMA channel 8 transfer complete
 243         dma_ch9_isr,                                    // 25 DMA channel 9 transfer complete
 244         dma_ch10_isr,                                   // 26 DMA channel 10 transfer complete
 245         dma_ch11_isr,                                   // 27 DMA channel 10 transfer complete
 246         dma_ch12_isr,                                   // 28 DMA channel 10 transfer complete
 247         dma_ch13_isr,                                   // 29 DMA channel 10 transfer complete
 248         dma_ch14_isr,                                   // 30 DMA channel 10 transfer complete
 249         dma_ch15_isr,                                   // 31 DMA channel 10 transfer complete
 250         dma_error_isr,                                  // 32 DMA error interrupt channel
 251         unused_isr,                                     // 33 --
 252         flash_cmd_isr,                                  // 34 Flash Memory Command complete
 253         flash_error_isr,                                // 35 Flash Read collision
 254         low_voltage_isr,                                // 36 Low-voltage detect/warning
 255         wakeup_isr,                                     // 37 Low Leakage Wakeup
 256         watchdog_isr,                                   // 38 Both EWM and WDOG interrupt
 257         unused_isr,                                     // 39 --
 258         i2c0_isr,                                       // 40 I2C0
 259         i2c1_isr,                                       // 41 I2C1
 260         spi0_isr,                                       // 42 SPI0
 261         spi1_isr,                                       // 43 SPI1
 262         unused_isr,                                     // 44 --
 263         can0_message_isr,                               // 45 CAN OR'ed Message buffer (0-15)
 264         can0_bus_off_isr,                               // 46 CAN Bus Off
 265         can0_error_isr,                                 // 47 CAN Error
 266         can0_tx_warn_isr,                               // 48 CAN Transmit Warning
 267         can0_rx_warn_isr,                               // 49 CAN Receive Warning
 268         can0_wakeup_isr,                                // 50 CAN Wake Up
 269         i2s0_tx_isr,                                    // 51 I2S0 Transmit
 270         i2s0_rx_isr,                                    // 52 I2S0 Receive
 271         unused_isr,                                     // 53 --
 272         unused_isr,                                     // 54 --
 273         unused_isr,                                     // 55 --
 274         unused_isr,                                     // 56 --
 275         unused_isr,                                     // 57 --
 276         unused_isr,                                     // 58 --
 277         unused_isr,                                     // 59 --
 278         uart0_lon_isr,                                  // 60 UART0 CEA709.1-B (LON) status
 279         uart0_status_isr,                               // 61 UART0 status
 280         uart0_error_isr,                                // 62 UART0 error
 281         uart1_status_isr,                               // 63 UART1 status
 282         uart1_error_isr,                                // 64 UART1 error
 283         uart2_status_isr,                               // 65 UART2 status
 284         uart2_error_isr,                                // 66 UART2 error
 285         unused_isr,                                     // 67 --
 286         unused_isr,                                     // 68 --
 287         unused_isr,                                     // 69 --
 288         unused_isr,                                     // 70 --
 289         unused_isr,                                     // 71 --
 290         unused_isr,                                     // 72 --
 291         adc0_isr,                                       // 73 ADC0
 292         adc1_isr,                                       // 74 ADC1
 293         cmp0_isr,                                       // 75 CMP0
 294         cmp1_isr,                                       // 76 CMP1
 295         cmp2_isr,                                       // 77 CMP2
 296         ftm0_isr,                                       // 78 FTM0
 297         ftm1_isr,                                       // 79 FTM1
 298         ftm2_isr,                                       // 80 FTM2
 299         cmt_isr,                                        // 81 CMT
 300         rtc_alarm_isr,                                  // 82 RTC Alarm interrupt
 301         rtc_seconds_isr,                                // 83 RTC Seconds interrupt
 302         pit0_isr,                                       // 84 PIT Channel 0
 303         pit1_isr,                                       // 85 PIT Channel 1
 304         pit2_isr,                                       // 86 PIT Channel 2
 305         pit3_isr,                                       // 87 PIT Channel 3
 306         pdb_isr,                                        // 88 PDB Programmable Delay Block
 307         usb_isr,                                        // 89 USB OTG
 308         usb_charge_isr,                                 // 90 USB Charger Detect
 309         unused_isr,                                     // 91 --
 310         unused_isr,                                     // 92 --
 311         unused_isr,                                     // 93 --
 312         unused_isr,                                     // 94 --
 313         unused_isr,                                     // 95 --
 314         unused_isr,                                     // 96 --
 315         dac0_isr,                                       // 97 DAC0
 316         unused_isr,                                     // 98 --
 317         tsi0_isr,                                       // 99 TSI0
 318         mcg_isr,                                        // 100 MCG
 319         lptmr_isr,                                      // 101 Low Power Timer
 320         unused_isr,                                     // 102 --
 321         porta_isr,                                      // 103 Pin detect (Port A)
 322         portb_isr,                                      // 104 Pin detect (Port B)
 323         portc_isr,                                      // 105 Pin detect (Port C)
 324         portd_isr,                                      // 106 Pin detect (Port D)
 325         porte_isr,                                      // 107 Pin detect (Port E)
 326         unused_isr,                                     // 108 --
 327         unused_isr,                                     // 109 --
 328         software_isr,                                   // 110 Software interrupt
 329 #endif
 330 };
 331
 332 //void usb_isr(void)
 333 //{
 334 //}
 335
 336 __attribute__ ((section(".flashconfig"), used))
 337 const uint8_t flashconfigbytes[16] = {
 338         0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
 339         0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0xFF, 0xFF, 0xFF
 340 };
 341
 342
 343 // Automatically initialize the RTC.  When the build defines the compile
 344 // time, and the user has added a crystal, the RTC will automatically
 345 // begin at the time of the first upload.
 346 #ifndef TIME_T
 347 #define TIME_T 1349049600 // default 1 Oct 2012 (never used, Arduino sets this)
 348 #endif
 349 extern void rtc_set(unsigned long t);
 350
 351
 352 static void startup_default_early_hook(void) { WDOG_STCTRLH = WDOG_STCTRLH_ALLOWUPDATE; }
 353 static void startup_default_late_hook(void) {}
 354 void startup_early_hook(void)           __attribute__ ((weak, alias("startup_default_early_hook")));
 355 void startup_late_hook(void)            __attribute__ ((weak, alias("startup_default_late_hook")));
 356
 357 __attribute__ ((section(".startup")))
 358 void ResetHandler(void)
 359 {
 360         uint32_t *src = &_etext;
 361         uint32_t *dest = &_sdata;
 362         unsigned int i;
 363
 364         WDOG_UNLOCK = WDOG_UNLOCK_SEQ1;
 365         WDOG_UNLOCK = WDOG_UNLOCK_SEQ2;
 366         asm volatile ("nop");
 367         asm volatile ("nop");
 368         // programs using the watchdog timer or needing to initialize hardware as
 369         // early as possible can implement startup_early_hook()
 370         startup_early_hook();
 371
 372         // enable clocks to always-used peripherals
 373 #if defined(__MK20DX128__)
 374         SIM_SCGC5 = 0x00043F82;         // clocks active to all GPIO
 375         SIM_SCGC6 = SIM_SCGC6_RTC | SIM_SCGC6_FTM0 | SIM_SCGC6_FTM1 | SIM_SCGC6_ADC0 | SIM_SCGC6_FTFL;
 376 #elif defined(__MK20DX256__)
 377         SIM_SCGC3 = SIM_SCGC3_ADC1 | SIM_SCGC3_FTM2;
 378         SIM_SCGC5 = 0x00043F82;         // clocks active to all GPIO
 379         SIM_SCGC6 = SIM_SCGC6_RTC | SIM_SCGC6_FTM0 | SIM_SCGC6_FTM1 | SIM_SCGC6_ADC0 | SIM_SCGC6_FTFL;
 380 #endif
 381
 382         // if the RTC oscillator isn't enabled, get it started early
 383         if (!(RTC_CR & RTC_CR_OSCE)) {
 384                 RTC_SR = 0;
 385                 RTC_CR = RTC_CR_SC16P | RTC_CR_SC4P | RTC_CR_OSCE;
 386         }
 387
 388         // release I/O pins hold, if we woke up from VLLS mode
 389         if (PMC_REGSC & PMC_REGSC_ACKISO) PMC_REGSC |= PMC_REGSC_ACKISO;
 390
 391         // TODO: do this while the PLL is waiting to lock....
 392         while (dest < &_edata) *dest++ = *src++;
 393         dest = &_sbss;
 394         while (dest < &_ebss) *dest++ = 0;
 395         SCB_VTOR = 0;   // use vector table in flash
 396
 397         // default all interrupts to medium priority level
 398         for (i=0; i < NVIC_NUM_INTERRUPTS; i++) NVIC_SET_PRIORITY(i, 128);
 399
 400         // start in FEI mode
 401         // enable capacitors for crystal
 402         OSC0_CR = OSC_SC8P | OSC_SC2P;
 403         // enable osc, 8-32 MHz range, low power mode
 404         MCG_C2 = MCG_C2_RANGE0(2) | MCG_C2_EREFS;
 405         // switch to crystal as clock source, FLL input = 16 MHz / 512
 406         MCG_C1 =  MCG_C1_CLKS(2) | MCG_C1_FRDIV(4);
 407         // wait for crystal oscillator to begin
 408         while ((MCG_S & MCG_S_OSCINIT0) == 0) ;
 409         // wait for FLL to use oscillator
 410         while ((MCG_S & MCG_S_IREFST) != 0) ;
 411         // wait for MCGOUT to use oscillator
 412         while ((MCG_S & MCG_S_CLKST_MASK) != MCG_S_CLKST(2)) ;
 413         // now we're in FBE mode
 414         // config PLL input for 16 MHz Crystal / 4 = 4 MHz
 415         MCG_C5 = MCG_C5_PRDIV0(3);
 416         // config PLL for 96 MHz output
 417         MCG_C6 = MCG_C6_PLLS | MCG_C6_VDIV0(0);
 418         // wait for PLL to start using xtal as its input
 419         while (!(MCG_S & MCG_S_PLLST)) ;
 420         // wait for PLL to lock
 421         while (!(MCG_S & MCG_S_LOCK0)) ;
 422         // now we're in PBE mode
 423 #if F_CPU == 96000000
 424         // config divisors: 96 MHz core, 48 MHz bus, 24 MHz flash
 425         SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(0) | SIM_CLKDIV1_OUTDIV2(1) |  SIM_CLKDIV1_OUTDIV4(3);
 426 #elif F_CPU == 48000000
 427         // config divisors: 48 MHz core, 48 MHz bus, 24 MHz flash
 428         SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(1) | SIM_CLKDIV1_OUTDIV2(1) |  SIM_CLKDIV1_OUTDIV4(3);
 429 #elif F_CPU == 24000000
 430         // config divisors: 24 MHz core, 24 MHz bus, 24 MHz flash
 431         SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(3) | SIM_CLKDIV1_OUTDIV2(3) |  SIM_CLKDIV1_OUTDIV4(3);
 432 #else
 433 #error "Error, F_CPU must be 96000000, 48000000, or 24000000"
 434 #endif
 435         // switch to PLL as clock source, FLL input = 16 MHz / 512
 436         MCG_C1 = MCG_C1_CLKS(0) | MCG_C1_FRDIV(4);
 437         // wait for PLL clock to be used
 438         while ((MCG_S & MCG_S_CLKST_MASK) != MCG_S_CLKST(3)) ;
 439         // now we're in PEE mode
 440         // configure USB for 48 MHz clock
 441         SIM_CLKDIV2 = SIM_CLKDIV2_USBDIV(1); // USB = 96 MHz PLL / 2
 442         // USB uses PLL clock, trace is CPU clock, CLKOUT=OSCERCLK0
 443         SIM_SOPT2 = SIM_SOPT2_USBSRC | SIM_SOPT2_PLLFLLSEL | SIM_SOPT2_TRACECLKSEL | SIM_SOPT2_CLKOUTSEL(6);
 444
 445         // initialize the SysTick counter
 446         SYST_RVR = (F_CPU / 1000) - 1;
 447         SYST_CSR = SYST_CSR_CLKSOURCE | SYST_CSR_TICKINT | SYST_CSR_ENABLE;
 448
 449         //init_pins();
 450         __enable_irq();
 451
 452         _init_Teensyduino_internal_();
 453         if (RTC_SR & RTC_SR_TIF) rtc_set(TIME_T);
 454
 455         __libc_init_array();
 456
 457 /*
 458         for (ptr = &__init_array_start; ptr < &__init_array_end; ptr++) {
 459                 (*ptr)();
 460         }
 461 */
 462         startup_late_hook();
 463         main();
 464         while (1) ;
 465 }
 466
 467 // TODO: is this needed for c++ and where does it come from?
 468 /*
 469 void _init(void)
 470 {
 471 }
 472 */
 473
 474 char *__brkval = (char *)&_ebss;
 475
 476 void * _sbrk(int incr)
 477 {
 478         //static char *heap_end = (char *)&_ebss;
 479         //char *prev = heap_end;
 480         //heap_end += incr;
 481
 482         char *prev = __brkval;
 483         __brkval += incr;
 484         return prev;
 485 }
 486
 487 __attribute__((weak))
 488 int _read(int file, char *ptr, int len)
 489 {
 490         return 0;
 491 }
 492
 493 /*  moved to Print.cpp, to support Print::printf()
 494 __attribute__((weak))
 495 int _write(int file, char *ptr, int len)
 496 {
 497         return 0;
 498 }
 499 */
 500
 501 __attribute__((weak))
 502 int _close(int fd)
 503 {
 504         return -1;
 505 }
 506
 507 #include <sys/stat.h>
 508
 509 __attribute__((weak))
 510 int _fstat(int fd, struct stat *st)
 511 {
 512         st->st_mode = S_IFCHR;
 513         return 0;
 514 }
 515
 516 __attribute__((weak))
 517 int _isatty(int fd)
 518 {
 519         return 1;
 520 }
 521
 522 __attribute__((weak))
 523 int _lseek(int fd, long long offset, int whence)
 524 {
 525         return -1;
 526 }
 527
 528 __attribute__((weak))
 529 void _exit(int status)
 530 {
 531         while (1);
 532 }
 533
 534 __attribute__((weak))
 535 void __cxa_pure_virtual()
 536 {
 537         while (1);
 538 }
 539
 540 __attribute__((weak))
 541 int __cxa_guard_acquire (char *g)
 542 {
 543         return !(*g);
 544 }
 545
 546 __attribute__((weak))
 547 void __cxa_guard_release(char *g)
 548 {
 549         *g = 1;
 550 }
 551
 552 int nvic_execution_priority(void)
 553 {
 554         int priority=256;
 555         uint32_t primask, faultmask, basepri, ipsr;
 556
 557         // full algorithm in ARM DDI0403D, page B1-639
 558         // this isn't quite complete, but hopefully good enough
 559         asm volatile("mrs %0, faultmask\n" : "=r" (faultmask)::);
 560         if (faultmask) return -1;
 561         asm volatile("mrs %0, primask\n" : "=r" (primask)::);
 562         if (primask) return 0;
 563         asm volatile("mrs %0, ipsr\n" : "=r" (ipsr)::);
 564         if (ipsr) {
 565                 if (ipsr < 16) priority = 0; // could be non-zero
 566                 else priority = NVIC_GET_PRIORITY(ipsr - 16);
 567         }
 568         asm volatile("mrs %0, basepri\n" : "=r" (basepri)::);
 569         if (basepri > 0 && basepri < priority) priority = basepri;
 570         return priority;
 571 }
 572