× Fuse settings Bootloader settings

Fuse Settings

Fuse Value Remarks
BOD 2.7V You may want to disable BOD for low power applications.
OCDEN ☐ Not used. can be used for on chip debugging
JTAGEN ☐ This fuse is for JTAG debugging
SPIEN ☐ Enable Serial program and data downloading. This setting is required for using bootloader
WDTON ☑ Watchdog timer is on.
EESAVE ☐ Select to save EEPROM memory on chip erase
BOOTSZ 4096 words Bootloader size. set to 512 words if not using the bootloader
BOOTRST ☑ select to use the bootloader.
CKDIV8 ☐ Divide clock by 8
CKOUT ☐ Not used.
SUT_CKSEL 8 MHz, 16K CK + 65ms  

The microprocessor is shipped with internal RC oscillator and with the fuse CKDIV8 programmed resulting in 1 MHz clock. The startup time is set to maximum and timeout period enabled. So for reprogram fuse with or without yuktix bootloader following setting should be followed

Fuse register values
Extended HIGH LOW Remarks
0xFD 0xC8 0xFF Default fuse settings for Yuktix PCB

important
FUSE Register bits is 0 → programmed and 1 → not programmed.

Makefile for bootloader 

                    
                        
        # MCU=
        # Processor frequency.
        #     This will define a symbol, F_CPU, in all source code files equal to the 
        #     processor frequency. You can then use this symbol in your source code to 
        #     calculate timings. Do NOT tack on a 'UL' at the end, this will be done
        #     automatically to create a 32-bit value in your source code.
        # ========================================
        #
        # rjha@yuktix.com
        # make changes for target here
        # BOOTLOADER_ADDRESS depends on BOOTSIZE inside source.
        # _______________
        # |___________|4K| 
        #
        #
        # 2560V 0x3F000 (256kb - 4kb = 252kb = 252x1024 = 0x3F000)
        # 1284P 0x3F000 (128kb - 4kb = 124kb = 124x1024 = 0x1F000)
        #  640P 0x3F000 ( 64kb - 4kb =  60kb =  60x1024 = 0xF000)
        #
        #
        F_CPU = 8000000
        MCU = atmega1284p
        BOOTLOADER_ADDRESS = 0x1F000                               
        # =======================================


        # Bootloader
        # Output format. (can be srec, ihex, binary)
        FORMAT = ihex

        # Target file name (without extension).
        TARGET = stk500boot2
Compile bootloader for ATMEGA1284P

  1. Checkout arduino stk500 bootloader repo on your disk.
  2. cd to repo folder
  3. Change makefile to match architecture (atmega1284p) and F_CPU and bootloader address as shown above
  4. compile bootloader hex using makefile (default target, just type $make)
  5. This should create a stk500boot.hex file
  6. Burn the bootloader using ATMEL ICE on your PCB

Upload bootloader using ATMEL ICE
  1. Connect Atmel ICE to PCB ICSP pins (refer to PCB pinout diagram)
  2. Make sure ATMEL ICE connector is mating with ICSP header
  3. Download Atmel studio
  4. Open Atmel studio and go to Tools → Device programming.
atmel studio tools

Now a screen will open where you can change the fuse settings and select the bootloader to be uploaded.

Upload settings

Upload hex files using bootloader

Use an in system programmer like AVRDUDE on your PC to upload application hex files with a bootloader. The bootloader should have been uploaded to the PCB using ATMEL ICE and BOOTRST FUSE setting should be enabled. You need to connect a serial cable to the DEBUG PORT (see the PCB pinout diagram) The connections are shown below for the FTDI RS232-TTL cable.

Red
Vcc NC Do not connect
Orange
Tx 1 MCU Rx
Yellow
Rx 2 MCU Tx
Black
GND 3,4  

The command line for avrdude is show below. You can put this in your makefile. 

                     $avrdude -C avrdude.conf -v  -patmega1284p -cwiring -P /dev/tty.usb0 -b38400 -D -Uflash:w:$(hex file name).hex:i

Common Gotchas

Low target voltage detected in atmel studio
  1. The Board is not powered ON
  2. ISP pins may not connected properly. check Vcc, MISO, MOSI, RST, Gnd, and SCK pins
  3. RESET pin may always be in pulled down state, triggering a RESET. check the RESET line.
Device signature not matching
  1. Select right MCU name
  2. Check ISP pin connections
avrdude: ser_open(): can't open device "\\.\COM4": The system cannot find the file specified
Select the correct COM port option with -P switch on command line
avrdude: ser_open(): can't open device "\\.\COM4": Access is denied
Some other process is using the same COM port. stop that process and try again.
avrdude: stk500v2_ReceiveMessage(): timeout avrdude: stk500v2_getsync(): timeout communicating with programmer
  1. Board is not powered ON, turn ON the power.
  2. Reset button is not pressed before uploading the code.
  3. Check the cable connections for Rx, Tx and ground
  4. Check that you are using correct UART PORT.