oddWires

If you've ever had problems getting your sketch or program onto an Arduino board or ATMega chip you may find this post useful. Error messages you may have seen include:

avrdude:stk500:_getsync():not in sync:
STK500 Failed!

Not very helpful are they?

In order to understand what's happening we need to know that we have two sides of the communication, on the host machine we have avrdude, a program for communicating with an AVR chip programmer. One of the programmers it supports is the STK500 - an ATMEL standard AVR board including a programmer (now replaced by the STK600). ATMEL have other programmers (AVRISP) and debuggers (DRAGON) which can also be used.

In the Arduino environment the boot-loader handles the programming task. It does it by simulating a subset of the STK500 programmer. The particular boot-loader used varies by the board. The Uno uses the optiboot boot-loader. You can find the sources in your Arduino package (optiboot.c). To help understand what follows, look at this extract from stk500.h which defines the various operations that the boot-loader can perform (not all of them are implemented).

/* STK500 constants list, from AVRDUDE */
#define STK_OK              0x10
#define STK_FAILED          0x11 // Not used
#define STK_UNKNOWN         0x12 // Not used
#define STK_NODEVICE        0x13 // Not used
#define STK_INSYNC          0x14 // ' '
#define STK_NOSYNC          0x15 // Not used
#define ADC_CHANNEL_ERROR   0x16 // Not used
#define ADC_MEASURE_OK      0x17 // Not used
#define PWM_CHANNEL_ERROR   0x18 // Not used
#define PWM_ADJUST_OK       0x19 // Not used
#define CRC_EOP             0x20 // 'SPACE'
#define STK_GET_SYNC        0x30 // '0'
#define STK_GET_SIGN_ON     0x31 // '1'
#define STK_SET_PARAMETER   0x40 // '@'
#define STK_GET_PARAMETER   0x41 // 'A'
#define STK_SET_DEVICE      0x42 // 'B'
#define STK_SET_DEVICE_EXT 0x45 // 'E'
#define STK_ENTER_PROGMODE 0x50 // 'P'
#define STK_LEAVE_PROGMODE 0x51 // 'Q'
#define STK_CHIP_ERASE      0x52 // 'R'
#define STK_CHECK_AUTOINC   0x53 // 'S'
#define STK_LOAD_ADDRESS    0x55 // 'U'
#define STK_UNIVERSAL       0x56 // 'V'
#define STK_PROG_FLASH      0x60 // '`'
#define STK_PROG_DATA       0x61 // 'a'
#define STK_PROG_FUSE       0x62 // 'b'
#define STK_PROG_LOCK       0x63 // 'c'
#define STK_PROG_PAGE       0x64 // 'd'
#define STK_PROG_FUSE_EXT   0x65 // 'e'
#define STK_READ_FLASH      0x70 // 'p'
#define STK_READ_DATA       0x71 // 'q'
#define STK_READ_FUSE       0x72 // 'r'
#define STK_READ_LOCK       0x73 // 's'
#define STK_READ_PAGE       0x74 // 't'
#define STK_READ_SIGN       0x75 // 'u'
#define STK_READ_OSCCAL     0x76 // 'v'
#define STK_READ_FUSE_EXT   0x77 // 'w'
#define STK_READ_OSCCAL_EXT 0x78 // 'x'

So how do these get used? First thing to do is switch avrdude verbose output on in the Arduino IDE and you'll get a lot more output. Here's an annotated commentary of the Blink sketch being loaded onto an Uno board. The process is going to be very similar for any other sketch.
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Blink Sketch AVRDUDE Ouput

Compilation section

…

Boot-loader section

avrdude command

/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/avrdude -C/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega328p -carduino -P/dev/tty.usbserial-A501DZOW -b115200 -D -Uflash:w:/var/folders/c_/zfn4h4215bdcv1473qb41j6h0000gn/T/build1586737504844891289.tmp/Blink.cpp.hex:i

This says:

Be really verbose, the part is atmega328p, the programmer is arduino, then the port name, then the USB baud rate setting, disable auto-erase, flash with the blink hex file.

Avrdude output

avrdude: Version 5.11, compiled on Sep 2 2011 at 18:52:52

No configuration file (usual for Arduino)

System wide configuration file is "/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"

User configuration file is "/Users/ian/.avrduderc"

User configuration file does not exist or is not a regular file, skipping

Name of the port

Using Port : /dev/tty.usbserial-A501DZOW

Using Arduino as programmer

Using Programmer : Arduino

Baud rate 115200

Overriding Baud Rate : 115200

Is anyone home? Is anyone home? Is anyone home? (STK_GET_SYNC, CRC_EOP)

avrdude: Send: 0 [30] [20]

Next two lines says yes (this is the boot-loaders do nothing response and says you are talking to it)

avrdude: Recv: . [14] (STK_INSYNC, STK_OK)

avrdude: Recv: . [10]

If avrdude does not receive this sequence then you will get the message: avrdude:stk500:_getsync():not in sync: (you can also get this later if avrdude times out waiting for data or confirmation of receipt. If you get this message all you know is that communication is not being made - it does not tell you why. There are, unfortunately, a lot of reasons why you can get this and you need to check all the obvious ones first (I know that you wouldn't make these mistakes but I have at some point or other - make sure you're using right port, baud rate, chip the right way around, tx/rx connections correct, common earth to USB, power to board etc.).

If you're getting correct response at this point then use the output below to identify where your failure is.

This is the data being used to program the part depends on board you have selected.

AVR Part : ATMEGA328P

Chip Erase delay : 9000 us

PAGEL : PD7

BS2 : PC2

RESET disposition : dedicated

RETRY pulse : SCK

serial program mode : yes

parallel program mode : yes

Timeout : 200

StabDelay : 100

CmdexeDelay : 25

SyncLoops : 32

ByteDelay : 0

PollIndex : 3

PollValue : 0x53

Memory Detail :

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