Machine Digital Read Out Teensie Arduine Hack

This is some advanced bootloader tweaks - 99% of Arduino users should not mess with their bootloader! Only for the wild at centre!

Bootloader for the Atmega328

Here is the parcel for a 'stock-still up' ATmega328 bootloader. To program it you may need to change the Makefile's ISPTOOL, etc definitions. The commands are make adaboot328; make TARGET=adaboot328 isp328 (I couldn't get the default 'isp' target to piece of work then I made a new one).

This version has a few fixes: get-go it integrates the 'no-look' and 'no-hang' fixes below. It also fixes the abrasive "missing signature bytes" problems that freaks out avrdude when programming without the IDE. I besides repaired the EEPROM code so that now you lot tin upload and download the EEPROM retentivity too as flash. Finally, theres a 'upload feedback' using the LED, for arduino clones that don't take TX/RX leds.

Please note that the fuses are different for this chip because of the extended retentivity!

"No-Wait" Bootloader

Here's a bootloader hack that will automatically starting time the sketch after it has been uploaded and will too simply showtime the bootloader when the reset button is pressed (so when you plug in power it will go straight to the sketch).

Copy the following lines:

ch = MCUSR;     MCUSR = 0;      WDTCSR |= _BV(WDCE) | _BV(WDE);     WDTCSR = 0;      // Bank check if the WDT was used to reset, in which case we dont bootload and skip straight to the lawmaking. woot.     if (! (ch &  _BV(EXTRF))) // if its a not an external reset...       app_start();  // skip bootloader

ch = MCUSR;     MCUSR = 0;      WDTCSR |= _BV(WDCE) | _BV(WDE);     WDTCSR = 0;      // Check if the WDT was used to reset, in which case we dont bootload and skip direct to the code. woot.     if (! (ch &  _BV(EXTRF))) // if its a not an external reset...       app_start();  // skip bootloader

And paste them as shown:

/* main program starts hither */ int main(void) {     uint8_t ch,ch2;     uint16_t w;      ch = MCUSR;     MCUSR = 0;      WDTCSR |= _BV(WDCE) | _BV(WDE);     WDTCSR = 0;      // Check if the WDT was used to reset, in which case nosotros dont bootload and skip directly to the code. woot.     if (! (ch &  _BV(EXTRF))) // if its a not an external reset...       app_start();  // skip bootloader      /* set pin management for bootloader pin and enable pullup */     /* for ATmega128, two pins need to be initialized */

/* chief program starts here */ int main(void) {     uint8_t ch,ch2;     uint16_t w;      ch = MCUSR;     MCUSR = 0;      WDTCSR |= _BV(WDCE) | _BV(WDE);     WDTCSR = 0;      // Check if the WDT was used to reset, in which case we dont bootload and skip straight to the code. woot.     if (! (ch &  _BV(EXTRF))) // if its a not an external reset...       app_start();  // skip bootloader      /* set pin direction for bootloader pin and enable pullup */     /* for ATmega128, two pins need to exist initialized */

Now, in the same way, copy the following code:

// autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (i); // 16 ms

// autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (1); // xvi ms

And paste information technology here:

/* Leave programming manner  */ 	else if(ch=='Q') { 	  nothing_response();  	  // autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (1); // sixteen ms 	} 	/* Erase device, don't care every bit nosotros will erase one page at a time anyway.  */ 	else if(ch=='R') { 	    nothing_response(); 	}

/* Leave programming manner  */ 	else if(ch=='Q') { 	  nothing_response();  	  // autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (1); // 16 ms 	} 	/* Erase device, don't intendance every bit we will erase ane page at a time anyway.  */ 	else if(ch=='R') { 	    nothing_response(); 	}

You can also just grab the source code and compiled hex file here.

It volition piece of work in NG or Diecimila Arduinos.

No-Hang Bootloader

If you are using a Diecimila with auto-reset you may be frustrated when your communications plan accidentally triggers the bootloader. Here is a quick hack to make the bootloader quit if it doesn't receive a '0' character offset (which would signal the Arduino software is trying to talk to information technology.

Copy the following line:

uint8_t firstchar = 0;

uint8_t firstchar = 0;

And paste:

/* main program starts here */ int main(void) {     uint8_t ch,ch2;     uint16_t w;     uint8_t firstchar = 0;

/* chief program starts hither */ int principal(void) {     uint8_t ch,ch2;     uint16_t w;     uint8_t firstchar = 0;

Copy:

firstchar = 1; // we got an advisable bootloader education

firstchar = one; // we got an appropriate bootloader pedagogy

Paste:

/* Hello is anyone home ? */  	if(ch=='0') { 	  firstchar = i; // we got an advisable bootloader instruction 	  nothing_response();

/* Howdy is anyone dwelling ? */  	if(ch=='0') { 	  firstchar = 1; // we got an appropriate bootloader educational activity 	  nothing_response();

Then paste this below the above code:

} else if (firstchar == 0) { 	  // the first character we got is not '0', lets bail! 	  // autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (1); // 16 ms 	}

} else if (firstchar == 0) { 	  // the start character nosotros got is non '0', lets bond! 	  // autoreset via watchdog (sneaky!) 	  WDTCSR = _BV(WDE); 	  while (1); // sixteen ms 	}

You can also just supersede the terminal 2 lines with app_start()

Upload Sketches with AVRDUDE

The bootloader is an 'stk500'-compatible, which means you can use expert ol' AVRDUDE to program the arduino.

Only plug in the USB cable, and so press the reset just before you beginning avrdude. If you need an avrdude tutorial, check out this page.

• Use -b 19200 to fix the baud rate to 19200
• The device signature reads dont seem to work and so you lot'll want to apply -F
• The developer blazon is avrisp
• The device blazon is -p m168
• The port is whatever the FTDI chip shows up every bit

This guide was first published on Jan 12, 2013. It was last updated on Jan 12, 2013.

This page (Bootloader) was last updated on Mar 03, 2022.

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Source: https://learn.adafruit.com/arduino-tips-tricks-and-techniques/bootloader