path: root/firmware/main.c

/* Name: main.c
 * Project: Micronucleus
 * Author: Jenna Fox
 * Creation Date: 2007-12-08
 * Tabsize: 4
 * Copyright: (c) 2012 Jenna Fox
 * All changes past revision 1.06 authored by http://github.com/cpldcpu
 * Portions Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH (USBaspLoader)
 * Portions Copyright: (c) 2012 Louis Beaudoin (USBaspLoader-tiny85)
 * License: GNU GPL v2 (see License.txt)
 *
 */
 
#define MICRONUCLEUS_VERSION_MAJOR 1
#define MICRONUCLEUS_VERSION_MINOR 10
// how many milliseconds should host wait till it sends another erase or write?
// needs to be above 4.5 (and a whole integer) as avr freezes for 4.5ms
#define MICRONUCLEUS_WRITE_SLEEP 8

// Use the old delay routines without NOP padding. This saves memory.
#define __DELAY_BACKWARD_COMPATIBLE__     

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/wdt.h>
#include <avr/boot.h>
#include <util/delay.h>

static void leaveBootloader() __attribute__((__noreturn__));

#include "bootloaderconfig.h"
#include "usbdrv/usbdrv.c"

/* ------------------------------------------------------------------------ */
// postscript are the few bytes at the end of programmable memory which store tinyVectors
// and used to in USBaspLoader-tiny85 store the checksum iirc
#define POSTSCRIPT_SIZE 6
#define PROGMEM_SIZE (BOOTLOADER_ADDRESS - POSTSCRIPT_SIZE) /* max size of user program */

// verify the bootloader address aligns with page size
#if BOOTLOADER_ADDRESS % SPM_PAGESIZE != 0
#  error "BOOTLOADER_ADDRESS in makefile must be a multiple of chip's pagesize"
#endif

#ifdef AUTO_EXIT_MS
#  if AUTO_EXIT_MS < (MICRONUCLEUS_WRITE_SLEEP * (BOOTLOADER_ADDRESS / SPM_PAGESIZE))
#    warning "AUTO_EXIT_MS is shorter than the time it takes to perform erase function - might affect reliability?"
#    warning "Try increasing AUTO_EXIT_MS if you have stability problems"
#  endif
#endif

// events system schedules functions to run in the main loop
static uchar events = 0; // bitmap of events to run
#define EVENT_ERASE_APPLICATION 1
#define EVENT_WRITE_PAGE        2
#define EVENT_EXECUTE           4

// controls state of events
#define fireEvent(event) events |= (event)
#define isEvent(event)   (events & (event))
#define clearEvents()    events = 0

// Definition of sei and cli without memory barrier keyword to prevent reloading of memory variables
#define sei() __asm__ __volatile__ ("sei")
#define cli() __asm__ __volatile__ ("cli")

uint16_t idlePolls = 0; // how long have we been idle?

static uint16_t vectorTemp[2]; // remember data to create tinyVector table before BOOTLOADER_ADDRESS
static uint16_t currentAddress; // current progmem address, used for erasing and writing

#if OSCCAL_RESTORE
 static uint8_t osccal_default;  // due to compiler insanity, having this as global actually saves memory
#endif 

/* ------------------------------------------------------------------------ */
static inline void eraseApplication(void);
static void writeFlashPage(void);
static void writeWordToPageBuffer(uint16_t data);
static uchar usbFunctionSetup(uchar data[8]);
static uchar usbFunctionWrite(uchar *data, uchar length);
static inline void leaveBootloader(void);

// erase any existing application and write in jumps for usb interrupt and reset to bootloader
//  - Because flash can be erased once and programmed several times, we can write the bootloader
//  - vectors in now, and write in the application stuff around them later.
//  - if vectors weren't written back in immediately, usb would fail.
static inline void eraseApplication(void) {
    // erase all pages until bootloader, in reverse order (so our vectors stay in place for as long as possible)
    // while the vectors don't matter for usb comms as interrupts are disabled during erase, it's important
    // to minimise the chance of leaving the device in a state where the bootloader wont run, if there's power failure
    // during upload
    
    uint8_t i;
    uint16_t ptr = BOOTLOADER_ADDRESS;
    cli();
    while (ptr) {
        ptr -= SPM_PAGESIZE;        
        boot_page_erase(ptr);
    }
    
    currentAddress = 0;
    for (i=0; i<8; i++) writeWordToPageBuffer(0xFFFF);  // Write first 8 words to fill in vectors.
    writeFlashPage();  // enables interrupts
}

// simply write currently stored page in to already erased flash memory
static void writeFlashPage(void) {
    cli();
    boot_page_write(currentAddress - 2);   // will halt CPU, no waiting required
    sei();
}

// clear memory which stores data to be written by next writeFlashPage call
#define __boot_page_fill_clear()   \
(__extension__({                                 \
    __asm__ __volatile__                         \
    (                                            \
        "sts %0, %1\n\t"                         \
        "spm\n\t"                                \
        :                                        \
        : "i" (_SFR_MEM_ADDR(__SPM_REG)),        \
          "r" ((uint8_t)(__BOOT_PAGE_FILL | (1 << CTPB)))     \
    );                                           \
}))

// write a word in to the page buffer, doing interrupt table modifications where they're required
static void writeWordToPageBuffer(uint16_t data) {
    uint8_t previous_sreg;
    
    // first two interrupt vectors get replaced with a jump to the bootloader's vector table
    // remember vectors or the tinyvector table 
        if (currentAddress == RESET_VECTOR_OFFSET * 2) {
            vectorTemp[0] = data;
            data = 0xC000 + (BOOTLOADER_ADDRESS/2) - 1;
        }
        
        if (currentAddress == USBPLUS_VECTOR_OFFSET * 2) {
            vectorTemp[1] = data;
            data = 0xC000 + (BOOTLOADER_ADDRESS/2) - 1;
        }
        
    // at end of page just before bootloader, write in tinyVector table
    // see http://embedded-creations.com/projects/attiny85-usb-bootloader-overview/avr-jtag-programmer/
    // for info on how the tiny vector table works
    if (currentAddress == BOOTLOADER_ADDRESS - TINYVECTOR_RESET_OFFSET) {
        data = vectorTemp[0] + ((FLASHEND + 1) - BOOTLOADER_ADDRESS)/2 + 2 + RESET_VECTOR_OFFSET;
    } else if (currentAddress == BOOTLOADER_ADDRESS - TINYVECTOR_USBPLUS_OFFSET) {
        data = vectorTemp[1] + ((FLASHEND + 1) - BOOTLOADER_ADDRESS)/2 + 1 + USBPLUS_VECTOR_OFFSET;
#if (!OSCCAL_RESTORE) && OSCCAL_16_5MHz   
    } else if (currentAddress == BOOTLOADER_ADDRESS - TINYVECTOR_OSCCAL_OFFSET) {
        data = OSCCAL;
#endif      
    }

    previous_sreg=SREG;    
    cli(); // ensure interrupts are disabled
    
    // clear page buffer as a precaution before filling the buffer on the first page
    // in case the bootloader somehow ran after user program and there was something
    // in the page buffer already
    if (currentAddress == 0x0000) __boot_page_fill_clear();
    boot_page_fill(currentAddress, data);
    
    // increment progmem address by one word
    currentAddress += 2;
    SREG=previous_sreg;
}

/* ------------------------------------------------------------------------ */
static uchar usbFunctionSetup(uchar data[8]) {
    usbRequest_t *rq = (void *)data;
    ((uint8_t*)&idlePolls)[1] = 0;              // reset idle polls when we get usb traffic
    
    static uchar replyBuffer[4] = {
        (((uint16_t)PROGMEM_SIZE) >> 8) & 0xff,
        ((uint16_t)PROGMEM_SIZE) & 0xff,
        SPM_PAGESIZE,
        MICRONUCLEUS_WRITE_SLEEP
    };
    
    if (rq->bRequest == 0) { // get device info
        usbMsgPtr = replyBuffer;
        return 4;
        
    } else if (rq->bRequest == 1) { // write page
        currentAddress = rq->wIndex.word;        
        return USB_NO_MSG; // hands off work to usbFunctionWrite
        
    } else if (rq->bRequest == 2) { // erase application
        fireEvent(EVENT_ERASE_APPLICATION);
        
    } else { // exit bootloader
#       if BOOTLOADER_CAN_EXIT
            fireEvent(EVENT_EXECUTE);
#       endif
    }
    
    return 0;
}

// read in a page over usb, and write it in to the flash write buffer
static uchar usbFunctionWrite(uchar *data, uchar length) {
    do {     
        // make sure we don't write over the bootloader!
        if (currentAddress >= BOOTLOADER_ADDRESS) break;
        
        writeWordToPageBuffer(*(uint16_t *) data);
        data += 2; // advance data pointer
        length -= 2;
    } while(length);
    
    // if we have now reached another page boundary, we're done
#if SPM_PAGESIZE<256
    // Hack to reduce code size
    uchar isLast = ((((uchar)currentAddress) % SPM_PAGESIZE) == 0);
#else
    uchar isLast = ((currentAddress % SPM_PAGESIZE) == 0);
#endif

    // definitely need this if! seems usbFunctionWrite gets called again in future usbPoll's in the runloop!
    if (isLast) fireEvent(EVENT_WRITE_PAGE); // ask runloop to write our page
    
    return isLast; // let vusb know we're done with this request
}

/* ------------------------------------------------------------------------ */
void PushMagicWord (void) __attribute__ ((naked)) __attribute__ ((section (".init3")));

// put the word "B007" at the bottom of the stack (RAMEND - RAMEND-1)
void PushMagicWord (void) {
    asm volatile("ldi r16, 0xB0"::);
    asm volatile("push r16"::);
    asm volatile("ldi r16, 0x07"::);
    asm volatile("push r16"::);
}

/* ------------------------------------------------------------------------ */
// reset system to a normal state and launch user program
static inline void leaveBootloader(void) {
    _delay_ms(10); // removing delay causes USB errors
    
    bootLoaderExit();
    cli();
    usbDeviceDisconnect();  /* Disconnect micronucleus */
    
    USB_INTR_ENABLE = 0;
    USB_INTR_CFG = 0;       /* also reset config bits */

    // clear magic word from bottom of stack before jumping to the app
    *(uint8_t*)(RAMEND) = 0x00; // A single write is sufficient to invalidate magic word
    
#if (!OSCCAL_RESTORE) && OSCCAL_16_5MHz   
    // adjust clock to previous calibration value, so user program always starts with same calibration
    // as when it was uploaded originally
    unsigned char stored_osc_calibration = pgm_read_byte(BOOTLOADER_ADDRESS - TINYVECTOR_OSCCAL_OFFSET);
    if (stored_osc_calibration != 0xFF && stored_osc_calibration != 0x00) {
        OSCCAL=stored_osc_calibration;
        asm volatile("nop");
    }
#endif
    // jump to application reset vector at end of flash
    asm volatile ("rjmp __vectors - 4");
}

int main(void) {
    /* initialize  */
    #if OSCCAL_RESTORE
        osccal_default = OSCCAL;
    #endif
    #if (!SET_CLOCK_PRESCALER) && LOW_POWER_MODE
        uint8_t prescaler_default = CLKPR;
    #endif
  
    bootLoaderInit();
    
#   if AUTO_EXIT_NO_USB_MS  
    ((uint8_t*)&idlePolls)[1]=((AUTO_EXIT_MS-AUTO_EXIT_NO_USB_MS) * 10UL)>>8; // write only high byte to save 6 bytes
#   endif   

    if (bootLoaderStartCondition()) {
    
        MCUSR=0;    /* need this to properly disable watchdog */
        wdt_disable();
 
        #if LOW_POWER_MODE
            // turn off clock prescalling - chip must run at full speed for usb
            // if you might run chip at lower voltages, detect that in bootLoaderStartCondition
            CLKPR = 1 << CLKPCE;
            CLKPR = 0;
        #endif
        
#       if  LED_PRESENT
            LED_INIT();
#       endif 

        usbDeviceDisconnect();  /* do this while interrupts are disabled */
        _delay_ms(500);  
        usbDeviceConnect();
        usbInit();    // Initialize INT settings after reconnect
        sei();        
        
        do {
            usbPoll();
            _delay_us(100);
            
            // these next two freeze the chip for ~ 4.5ms, breaking usb protocol
            // and usually both of these will activate in the same loop, so host
            // needs to wait > 9ms before next usb request
            if (isEvent(EVENT_ERASE_APPLICATION)) eraseApplication();
            if (isEvent(EVENT_WRITE_PAGE)) {
                _delay_us(2000); // Wait for USB traffic to finish before halting CPU with write-
                writeFlashPage();  
            }

#       if BOOTLOADER_CAN_EXIT            
            if (isEvent(EVENT_EXECUTE)) break; // when host requests device run uploaded program
#       endif        
            clearEvents();

#       if  LED_PRESENT
            LED_MACRO( ((uint8_t*)&idlePolls)[1] )
#       endif
                
        } while(bootLoaderCondition());  /* main event loop runs so long as bootLoaderCondition remains truthy */
    }
    
    // set clock prescaler to desired clock speed (changing from clkdiv8, or no division, depending on fuses)
    #if LOW_POWER_MODE
        #ifdef SET_CLOCK_PRESCALER
            CLKPR = 1 << CLKPCE;
            CLKPR = SET_CLOCK_PRESCALER;
        #else
            CLKPR = 1 << CLKPCE;
            CLKPR = prescaler_default;
        #endif
    #endif
    
#   if  LED_PRESENT
        LED_EXIT();
#   endif
    
#   if OSCCAL_RESTORE
    OSCCAL=osccal_default;
    asm volatile("nop");    // NOP to avoid CPU hickup during oscillator stabilization
#   endif

    leaveBootloader();
}
/* ------------------------------------------------------------------------ */