Atmega fusebit doctor (HVPP+HVSP) – fix the fusebits

mega_fusebit_doctor_1Atmega fusebit doctor, as name says it, device for repairing dead Atmega (and Attiny from v2.04) family AVRs by writing correct fusebits. Most common mistakes or problems are a wrong clock source (CKSEL fusebits), disabled SPI programming (SPIEN fuse) or disabled reset pin (RSTDISBL fuse). This simple and cheap circuit will fix you uC in a fraction of a second. If in first case we can help ourself with clock generator, then in 2nd and 3rd cases bring uC back to life is impossible with standard serial programmer. Most of people do not decide to build parallel programmer because its inconvenient and its cheaper and faster to buy new uC.

High voltage programming

mega_fusebit_doctor_3This circuit uses the parallel and serial high-voltage programming method. With those methods, we can talk to our “dead” chips which have reset or isp disabled:
HVPP = high voltage parallel programming.
HVSP = high voltage serial programming.

Supported chips list:
Code to this point supports 145 chips, but not all have been tested. Tested are lighted green. Report a problem – and i make a fix :)
AT90s1200, Attiny11, Attiny12, Attiny13/A, Attiny15
Attiny2313/A, Attiny24/A, Attiny26, Attiny261/A, Attiny28, AT90s2333, Attiny22, Attiny25, AT90s2313, AT90s2323, AT90s2343
Atmega48/A, Atmega48P/PA, Attiny461/A, Attiny43U, Attiny4313, Attiny44/A, Attiny48, AT90s4433, AT90s4414, AT90s4434, Attiny45
Atmega8515, Atmega8535, Atmega8/A, Atmega88/A, Atmega88P/PA, AT90pwm1, AT90pwm2, AT90pwm2B, AT90pwm3, AT90pwm3B, AT90pwm81, AT90usb82, Attiny84, Attiny85, Attiny861/A, Attiny87, Attiny88, AT90s8515, AT90s8535
Atmega16/A, Atmega16U2, Atmega16U4, Atmega16M1, Atmega161, Atmega162, Atmega163, Atmega164A, Atmega164P/PA, Atmega165A/P/PA, Atmega168/A, Atmega168P/PA, Atmega169A/PA, Attiny167, AT90pwm216, AT90pwm316, AT90usb162
Atmega32/A, Atmega32C1, Atmega323/A, Atmega32U2, Atmega32U4, Atmega32U6, Atmega32M1, Atmega324A, Atmega324P, Atmega324PA, Atmega325, Atmega3250, Atmega325A/PA, Atmega3250A/PA, Atmega328, Atmega328P, Atmega329, Atmega3290, Atmega329A/PA, Atmega3290A/PA, AT90can32
Atmega64/A, Atmega64C1, Atmega64M1, Atmega649, Atmega6490, Atmega649A/P, Atmega6490A/P, Atmega640, Atmega644/A, Atmega644P/PA, Atmega645, Atmega645A/P, Atmega6450, Atmega6450A/P, AT90usb646, AT90usb647, AT90can64
Atmega103, Atmega128/A, Atmega1280, Atmega1281, Atmega1284, Atmega1284P, AT90usb1286, AT90usb1287, AT90can128
Atmega2560, Atmega2561


mega_doctor_renderJust put your dead mega in socket, press the START button, and enjoy your good-as-new processor. There are three slots on board, for most common AVR’s, pins compatible with: Atmega8, Atmega16, Attiny2313. There is also an extra goldpin connector with all signals so you can attach adapters:
#1 adapter” as HVPP extension, for 20pin Attiny26 compatible and 40pin Atmega8515 compatible processors.
HVSP adapter” for 8pin and 14pin HVSP processors.
Or make your own adapters for other types of processors, in trough-hole or surface-mounted, you can use the breadboard for this – just connect signals to correct pins. How? Check your AVR datasheet, go to “memory programming” and then “parallel programming” – check the signal names, all signals are described under the DIP40 slot. In doctor memory there is a lot of free space so project may be developed all the time. One sided PCB with 55mm x 92mm dimensions. On top side you need to solder several jumpers, or, make this PCB as double sided – choose yourself. Resistors from R7 to R23 may be in 100ohm to 10K, but i suggest from 470ohm to 1K.

While mounting the DIP40 slot, you must to remove it pins from 29 to 37. These pins must not have electrical contact with inserted uC pins, traces runs there only to make the board smaller (onesided). Take a look at pic on the left, these you must remove from slot.


fusebit_doctor_adapters_4The ALLOW ERASE jumper allows doctor to erase whole flash and eeprom memory, if it is open, doctor will newer erase memory but may not cure device if lockbits are enabled, so you choose. After insert dead uC and press the START button, doctor will initiate the parallel or serial high-voltage programming mode. This is chosen automatically, device will recognize HVSP adapter and start to work in HVSP mode. After that, doctor wait for high state at RDY/BSY line. Then, read device signature and check if it supports it. Next, memory erase is performed if user allows that. Then lockbits are checked, and if they not blocking device, doctor sets all fusebits to fabric, having regard to whether there are extended fusebits or not. Some of older AVR have only one byte of fuses – LOW – and this is also included. After fusebits are verified, the proper leds is flashed.

Leds explanation:

green on – patient successfully cured, fusebits repaired. If lockbits are enabled, just verify fusebits with factory ones – and if they ok – light up green.
red on – signature problem, can’t read, no device in socket, or no such signature in database.
green flashing – signature ok, fusebits are wrong. Lockbits enabled, chip erase permission required (read below).
red flashing – signature ok, no lockbits, but for some reason can’t write new fusebits.


Note that terminal is not needed, device works without pc, and all we want to know we get from leds.
You can find extra RS232 output, and connecting this to the terminal, sends all information about fixing process – see exemplary printscreens in gallery. All the info is send “on fly” via uart. Use proper converter to connect this with pc. If you have COM port for RS232, use MAX232 based converter (eg this). If you are using laptop, use the USB converter (like this or this).

Terminal settings:
baudrate: 4800
parity: none
databits: 8
stopbits: 1
handshake: none


prototype_docUse one of the following microcontrollers as the doctor-chip: Atmega8, Atmega88, Atmega88P, Atmega168, Atmega168P, Atmega328, Atmega328P – and their newer/low-voltage “A” or “L” versions.
Use stabilized 12V supply voltage. Higher voltage can damage fixed chip!

Code was written based on high-voltage parallel and serial programming section of datasheet of suitable AVRs.
If you are searching for attiny family AVR’s fusebits fix device, then check my previous project, the Attiny fusebit doctor. Unfortunately, some bugs show off and this project is no longer updated since the “Atmega fusebit doctor” supports all the Attiny family AVRs. But, source code is attached for this project, and with avr datasheet, it will be easy to understand this programming mechanism.


Internal 1MHz clock, and enabled EESAVE bit – see README file.
If you use a brand new chips as doctor, you don’t need to change anything – 1MHz clock is already set as default. EESAVE bit is optional. It disallows to erase the eeprom when firmware is actualized, eeprom is used to store the fixed chips counter which is send trough uart.


Send your own fuses and locks trough terminal, talk with chips with broken signature. If you connect terminal Tx pin to PCB Rx pin – manual mode will be enabled automatically. This requires Tx-terminal pin to be HIGH and OUTPUT when idle. It must pull up the 10K pulldown. If this condition is not met, doctor will work in normal – automatic mode.

First, doctor will read signature. And if fail, it will ask to type signature manually.
Type two last bytes of signature in HEX (4 chars) and hit enter.

Then, doctor will try to read the chip depending on given signature.
When succeed, select an option:
1 – write fusebits – this will perform a fuse write cycle with fuse-values from buffer (default).
2 – modify fusebits – this will let you to type fuses manually, values in buffer will update. Type one byte in HEX (2 chars) and hit enter. Repeat for each byte (if exist).
3 – set lockbits – type new lock value in HEX (2 chars) and hit enter – do this with caution! Remember that unused bits are always 1! E.g. if want to enable LB1 and LB2, type FC (11111100)
4 – erase the chip – this will just erase the chip and locks, it require “allow erase” jumper for safety.
5 – end – exit programming and drop voltages, now you can safely remove the chip.

See how Attiny13 with broken signature was repaired.
See how the same chip was “broken” again.
Do not suggest LEDs when in manual mode – they just blinking randomly :)
ATTENTION – Firmware 2.1x NEED a pcb updated to version 2h!



DOWNLOAD – ARCHIVE of all previous updates. Firmwares + boards.
Changelog in README file. -SMD VERSION HERE-
No need to download this, all newest files are below.

DOWNLOAD – UPDATE #11, 30.04.2011:
Firmware ver.2.11 – fixes
Fusebits: see README file

Fixed bug when not writing the HIGH fusebyte (concerns all chips!)
“Just” a typo which i made during optimalisations for 2.10 firmware :)

Pads for 4 chips, compatible with: T2313, M8, M16, M128 – all has been tested.
Use strong paper clips to push chip to the pads.

FAQ – frequently asked Questions and Answers: (update 2014-02-01)

Q: No sign of life, no leds are working.
A: Critical bugs on pcb, poorly programmed chip.

Q: Red led is on.
A: Chip si not recognized. Make a voltage measurements. In idle, measure voltages on +12 RESET and +5 SUPPLY at female goldpin connector – you should get 0V or close to 0V on both. After the START button is pressed, you should get close to +12V and 5V for one second. If not, check transistors, if they are ok and if they are soldered ok.

Q: Red led is on.
A: Bugs on pcb, traces are packed densely and its very possible that you have invisible gap, shortcut, or dry joint. Check everything with multimeter, but PRECISELY.

Q: Red led is on.
A: Connect device to the terminal to get repair log. Press start to receive infos.

Q: Received “Init programming…” and nothing more – OR – received signature is “00 01 02″ or “FF FF FF”.
A: Chip is broken, or there still are bugs on pcb – look above.

Q: Received signature is “1E 90 00″, ” 1E 1E 1E”, or something familiar (meaningful data).
A: Chip is good, it initiates, look for shortcuts on DATA, BS, XA lines.

Q: Green led is on / “Verifying… – OK!” received, but chips don’t work with standard programmer.
A: You can be 100% sure that fuses are fixes, chip have hardware ISP damaged or it have some other damage.

Q: What are “Read Signature… FAIL!” and “Trying T2313 pinout… OK” doing in log?
A: Alle the 20pin chips need to be threated individually. First, device tries to read chip with standard schematic, and if it fails (“FAIL!”), then it tries to use schematic for 20pin T2313 compatible chips and then chip is read properly. This is normal behavior, this not a bug.

Q: What are “<[2J" trashes doing in log?
A: This is a terminal clear screen sequence, turn on the “VT-100″ emulation in terminal settings.

Q: I’m trying to type data into terminal but no chars appearing.
A:Make sure you set handshake to NONE in terminal settings.

Q: After typing data into the terminal, i can’t confirm them with return key and can’t type next ones.
A: When pressing return, your terminal must have to send the CRLF chars, if not, check your settings.

Q: This still doesn’t help me, i tried everything but still have the problem.
A: Ask in comments below :) Post firmware version and pcb version with which you try to work, paste the repair log.

Q: Do all these 1K series resistors (R7 up to R23) are really needed here?
A: No, you can build the circuit without them. But remember, if for some reason out patient will not enter in the programming mode and continue with its code, then logic state conflict will occur between two microcontrollers which can damage them permanently. These resistors are to protect the circuit against such situations. I strongly recommend to build it exactly as schematic says.

Q: Pulldown resistors for 12V and 5V lines (R24 and R27) are heating up quite strongly in manual mode, and whole circuit takes more power, can i change them for something higher value?
A: Yes, but circuit can work incorrectly with some of the patients. When idle, voltages should be near 0V, and when powering on or off, their edges should have proper steepness to provide good timing (see entering high voltage programming in datasheet). Because only simple bipolar transistors are used, these resistor guarantee above requirements. The interesting case is an attiny2313 problem when all the fuses were correctly burned, without one, the RSTDISBL. As it showed up, because of bad edges of 12V reset voltage, this uC although was working in parallel mode, but not in high voltage, so it was not allowing to change that fuse – this is my own interpretation so i can be wrong.

Q: My chip is read properly but doctor can not write new fuses, allow erase is enabled.
A: If the ISP programmer acts the same way, then your chip is damaged, nothing can do.

Q: Without a patient, circuit acts awkward, it freezes, and goes on when i put my finger near the traces.
A: This circuit is not meant to be used without a patient. It acts in such way because when entering in programming mode, it is waiting for a high state on the RDY pin from patient. This pin is not pulled down and works as high impedance input, so electrostatic charge from your finger is read as high state and code goes on further.

Q: Chip names are not appearing in the log, i see “no names in 8kB ver” instead.
A: Chip names are not displayed in 8kB versions of the firmware, i.e. for atmega8 and atmega88 – because names don’t fit in such memory space. If you want the names, use atmega168 or atmega328 chip and burn proper firmware.

ALWAYS use the newest version of the firmware. Hex and bin files are the flash memory files, use one of them. No need to program eeprom memory.

Русский перевод – Евгений из GetChip Блог.

Atmega fusebit doctor (HVPP+HVSP) – fix the fusebits
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  1. Fantasy, Did you set the jumper so it can Write?. Flashing green usually means signature ok, fusebits are wrong. Lockbits enabled, chip erase permission required. There is a guide up at top part of this page.

  2. Thank you for your wonderful project!!! i builded the circuit on breadboard and i rescued one atmega8A and one atmega328P (both dip socket). its working good. Then i used to try on TQFP ic’s and no luck! i double checked connections but same result. i connected pind from datasheet same as dip socket names. am i doing something wrong? thank you in advance…

  3. the socket oft the Mega16/32 is very near to the Tiny2313.
    So I can’t use it with Textool-sokets. Now I have made a external socket for the Mega16/32, and do not placed it on the main board.
    Maybe it is possible to make the 1k resistors smaller, so there is more place between M16/32 and T2313.
    I have stand up the 7805 to have more place for a additional 5-to-12-Volt-converter. Just single in line: GND, 5V in, GND, 12V out ;-)

  4. I am trying to revive an ATMEGA328p. I assambled everything on a breadboard (for IC1 I am using Atmega8 and my bricked Atmega328p is connected as IC4), I haven’t powered yet because I don’t understand one thing in the schematic: on IC4, in 9 is Xtal1 but on the IC2 Xtal1 is marked as pin 9 and as pin5 too. Which pin of IC2 do I have to use?

  5. Hoooray, it worked! My 328p is alive again. This little great device worked at the first try even my build was an sophisticated “octopus” breadboard :))

    • Hi, sorry for delay in answer, but i see you solved it out. It looks messy, no surprise you had problems with it :) This circuit is a bit tricky and should be made on a pcb, well you can make yourself one, you never know when it might be handy :)

    • @Admin
      Hello again,
      I built this great device on a dedicated PCB (you are so right, never know when it is needed) after I successfully previously tested on a breadboard. Even you shared the entire Eagle file, I preferred to redesign the hole board from scratch to fit my needs, I work more frequently with ATTINY13 DIP8 so I did not want to use any pinout adapter for these chips.
      OK, everything is working well as far as I tested, I could communicate with the PC, I could even write fuses manually for an ATMEGA8 chip… I guess the board is in working condition. Still, I have a problem… the board can’t “see” any of ATTINY13 chips. I tried 2 of them but no luck, the error message is something like “could not read signature… tried 2313 mode….” sorry but I can’t remember the exact error message.
      How do I connect the ATTINY13 chip? Are they OK as I highlighted with yellow in the picture I attached?
      I used the info in this archive: “UPDATE #11, 30.04.2011″

      Thank you!

    • I could not attached more pictures in the previous post so here’s my home-brew PCB :)…

    • … and this is my assembled board. I have one more question: I used a TO92 package for the 7805 IC (this is rated about 100mA), could this be a problem (besides the dissipated heat)? As I said, I tried to heal (as a matter of fact the chip was OK, I just made some tests) an ATMEGA8 and everything went OK.

    • Once again I’ve solved myself the problem: eventually I noticed that on SV2 pin row I had to connect pins 6 and 8 (OE and XTAL1). The the Doctor works with ATTINY13 too.

    • Hi.

      I see you figured it out. Yes XTAL1 and OE are the sensing lines for HVSP adapter. Remember that you need to disconnect them when repairing HVPP chip.

      78L05 is sufficient for this task, it will work.

      Very nice home made PCB build :)

    • OK, I don’t know too many advanced things about microcontrollers :(… I studied Attiny13’s datasheet and I was looking for some correspondent pins for high voltage programming, something as on doctor board: OE, RDY, BS1… but there where just SDI, SDO, SCI… and I did not know which goes to where. Well, in the meantime, I discovered that high voltage programming can be serial or parallel and some MCUs suport just one of them, like Attinny13 which works with HVSP. But what solved my problem was studying more closely your adapter schematics and only then I noticed the connection between those 2 pins (OE and XTAL1).

  6. where can purchase pcb please ?

    thank you

  7. Добрый день! Транзисторы bc557 обязательно должны быть установлены в инверсном режиме? На печатной плате перепутаны вход +12 В и выход относительно принципиальной схемы – это имеет значение? Спасибо.

  8. well, actually the baudrate for the serial is 38400, not 4800

  9. I’m using a ATmega328P-PU.
    Do I need to set any fuse bits

  10. Dear Mr.,

    I built the atmega hvpp fusebit doctor_update11 with its own printed circuit board and have the following questions:
    -what exactly from the red and green LED appears?
    – is necessary to change fusebits and lock bits using a terminal program or a reset to the factory settings only with the FUSEBIT DOCTOR is possible?
    – it is true that the voltage at IC2-PD7(AIN1) 5 volt and IC2-PD5(T1) is 0.03 volts when not actuated switch S1 and SV2 PIN11 11,995 Volt , SV2 PIN10 are to measure 4,9975 voltage?
    Or must, the voltage switch S2 is not actuated SV2 PIN11 and SV2 PIN10 be as described on your Web site, each about 0 Volts ?

    Best regards

  11. hi Dear
    i built this great project three years ago and its worked good. but it doesn’t work now!!
    both leds are off . i changed every part’s and built 2 new pcb but same result . I’m sure no Critical bugs on pcb . thanks for support

  12. Works like a charm! Thank you very much!

  13. Thank you *so* much. You rescued my ATmega1284P! I wired up a breadboard from the schematic and found programming highly unreliable until I removed the 100R pull-down on the +5V BC557 after which it worked first time. Thank-you!

  14. Mam problem z połączeniem z terminalem, jak nacisnę przycisk na płytce to w terminalu pojawiają mi się same zera.

    • Nie napisałem że firmware mam 2.11

    • Spróbuj może innego terminala? W tym jest taka mnogość opcji że łatwo o pomyłkę. I oczywiście używasz konwertera TTL a nie RS232?

      A jak nie, to spróbuj użyć innej atmegi jeśli masz, może w tej wewnętrzny zegar jest tak słabo skalibrowany że baudrate uartu za bardzo odbiega od tego ustawionego.

  15. Jakiego terminala używasz ? Jaki terminal nie ma tylu opcji, bo nie wiem zbytnio co wpisać w google.

  16. Tak używam konwertera RS ttl , na max232 którego kupiłem u chińczyka za 1$. Jak nie zadziała to sklece coś sam.

  17. hi
    locked ATmega8 a programmer or software needed to read and write

  18. Hello, where can i find the pcb for dip8 and 14 adapter?

  19. U ab_so_lu_te_ly ROCK!!!!
    fuse dead 328p cured by a 328p doctor

    thank you so much

  20. another happy camper here :)
    the PCB turned out AMAZING!
    still stuck on Init programming…, but Im confsure its just a stupid short circuit somewhere. I also have to remove some pins on the big mega tho.
    btw, PLASTIK laquer makes this board look sooooo nice :D

  21. I made this project and it works great, I ordered pcb and minimum order 3, so I have 2 to sell if anybody is interested. send me a email.

  22. Please share source code

  23. Witam, zmodyfikowałem sobie dość mocno Twoją płytkę (w zasadzie powstała od 0). Mógłbyś rzucić na to okiem? Może komuś oswojonemu z lutownicą ta płytka będzie odpowiadać. Na razie istnieje to tylko jako projekt, ale może się niedługo zmobilizuję i wykonam prototyp.

  24. Sory za syf w komentach, ale co chwile jakiś błąd wyskakuje.

  25. Hello. Your project is extremely usefull.
    My question is: did you tried to recover Arduino Pro Mini or Arduino Nano board?
    Do I need to unsolder something? For example R&C connected to Reset pin?
    Of course I need to connect Xtal pin somehow..

  26. I recovered 8515 by building the adapter board.
    worked great

  27. Hi, first awesome work dude! thi is a mad project!
    Can you please make a guide how to connect the lcd to it as you have on the Picture?

  28. Great job Pawel!
    I recovered DIL28 Atmega328P, Arduino Pro Mini M328P and also Arduino Nano M328P using your FuseBitDoctor.
    No extra soldering or desoldering needed on those Arduino boards.
    Only need is connecting XTAL1 pin using sharp needle.

    B.R. Lukas

  29. Super układ, naprawił mi fusebity w Atmega 328. Polecam! ;)

  30. I’m having device signature problem for ATmega1284P, my doctor chip ATmega8 detects it but when asked for manual entering of signature on serial terminal (1E 97 05 is signature for ATmega1284P), Doctor returns some garbage characters on terminal and dose not proceeds (Doctor chip Hangs).

    • Well i don’t know, your M1284P is NOT recognized at all, if it was, then doctor would not ask for manual signature. When typing signature in, type two last bytes and hit return, it should proceed. This garbage chars could be caused by UART timing error, maybe your mega8 is running far from 1MHz, maybe try another one? And try to test the circuit with some known good patient.

    • Thanks for reply Admin. I have tested my circuit with ATmega16 (patient), Doctor (Atmega8) recovered ATmega16 successfully. But the problem is ATmega16’s signature was detected by Doctor and for ATmega1284P it fails. I think my ATmega1284P is Damaged. And one more question, can i use ATmega8 firmware on ATmega8L TQFP ?

    • Yes of course you can, the L just stands for low-voltage version, all the logic is identical if the signature is the same.

      Your M1284P is permamently damaged or the connections are bad. A guy from previous comments confirms that this avr is working with doctor

  31. Great project! I made mine replacing the bc547 and bc557 by 2n3904 and 2n3906 and I did only have 0.1uf (104) capacitor for use with the 28 pins socket. It’s ok to do that?

    Also witch software you used to create the 3d model of the board?

  32. hi from France
    thank you for this tool , it saved me many times, the reset program via the serial port is a must

  33. I tested it with ATTINY2313 and ATTINY4313. Everything works good so 4313 should be change to green on list of supported devices.

  34. Miałem problemy z uruchomieniem układu, sygnatury były 01 02 03 jak z faq, układ przez rs232 zgłaszał wszystkie etapy ale nic się nie naprawiało. Sprawdzałem pod mikroskopem połączenia i luty, wszystko było ok. Sprawdziłem dla pewności testerem ciągłości w multimetrze i okazało się, że jedna ścieżka nie przewodzi prądu całkowicie, stwarza opór. Oglądałem ją dokładnie pod mikroskopem i wygląda najnormalniej w świecie, wsadziłem w to miejsce przewód izolowany łącząc ze sobą konkretne piny i układ zaczął działać jak należy, uratowałem od zapomnienia już 3 atmegi8 :-)


  35. Hi, first awesome work dude! thi is a mad project!
    Can you please make a guide how to connect the lcd to it as you have on the Picture?

  36. Cześć.

    Mam ATmega8 prawdopodobnie z uszkodzoną sygnaturą – AVRdude zawiesił się w trakcie programowania i klops. :(

    Fusebit Doctor (którego z powodzeniem stosuję już od roku) w wersji sprzed aktualizacji 2.1x niby naprawia ją (najpierw bardzo króciutko mignie czerwona, a następnie zielona dioda świeci się światłem ciągłym).

    Niestety pomimo tego programator nie rozpoznaje sygnatury tak naprawionego mikrokontrolera:

    avrdude.exe: set SCK frequency to 93750 Hz
    avrdude.exe: error: programm enable: target doesn’t answer. 1
    avrdude.exe: initialization failed, rc=-1
    avrdude.exe: AVR device initialized and ready to accept instructions
    avrdude.exe: Device signature = 0x000000
    avrdude.exe: Yikes! Invalid device signature.
    avrdude.exe: Expected signature for ATMEGA8 is 1E 93 07
    avrdude.exe done. Thank you.

    Mikrokontroler podłączony prawidłowo programator sprawny – inne Atmegi8 obsługuje bez problemu.

    Sądzę więc, że uszkodzeniu uległa sygnatura dlatego chcę zrobić wersję 2.1x by ją ręcznie ustawić. A może się mylę?

    Jak dokładnie rozumieć:

    “Wymaga to aby pin Tx terminala był w stanie wysokim w czasie bezczynności, musi on podciągnąć rezystor ściągający 10K. Jeśli tak się nie stanie (połączenie przychodzące odłączone) to doctor będzie pracował w trybie automatycznym (jak dotychczas).”

    Jak mam wymusić ten stan wysoki na pinie TX w terminalu (używam Realterm)?
    Jak rozumieć czas bezczynności?


    • Już sobie poradziłem. Układ miał wyzerowaną sygnaturę oraz fusebity, a stan wysoki na pinie TX wymusił port RS232 komputera. Dziękuję za czas, który poświęciłeś na opracowanie i upublicznienie Doctora :)

  37. My finished fusebit doctor. If helpful, I used ksp2222-NPN and PN2907A-PNP transistors, and Atmega 328P-PU Doctor chip. For resistor R7 to R23, used 470 ohm. Also used 470 ohm for R25 instead of 100 ohm pull down resistor; stays cool, only dissipates .05 watt instead of.25 watt, and communicates with Attiny 2313.

    • Terminal window from Attiny 2313. Just remember, if fusebit doctor is powered without patient chip, circuit will hang in initial programming, Just install patient and push start. If powered up with a patient chip in socket, fusebit doctor will reset Uc without pressing start button, then reset for next chip. If you want to read fuses of bricked Uc in terminal before reset, don’t power doctor with that chip installed in socket.

  38. hi i got 2 questions
    i was looking on pcb eagle after i removed the words to see whats done i notice there is 2 or 3 tracks that are not completed are they like that?
    also the atmega8 that then u will program it to burn the fuses, can it be used atmega328p or does it need to be the atmega8?

  39. sorry forgot to post pic with the missing track lines

    • Push RATSNEST button and ground plane will fill in missing ground traces. You can use Atmega 328, just need to burn fuses to L-62, H-D1, E- FF or 07 depending on programmer. Need to use correct .hex or binary file for chip you are using. Fuses for Atmega 8 are L-E1, H-D1. That information is in the readme file from update 11 ZIP, as well as all 8 series firmware files.

  40. awsome just seen it,im very new to this so sorry my question hehe
    yes ratsnake have field the ground traces, i see also the firmware for the 328p a bin file and a hex, how do i then set up the bin and hex file does the fuse doctor have a program or a arduino sketch to upload the correct info to the atmega chip?

    • You will need a programmer to flash the Atmega chip, there are numerous types available. I often use USBTINY 2313 programmer in conjunction with AVRDUDE in a command line. Spark fun has pocket programmer, cheap, and works great. There are numerous tutorials on spark fun ( that will help . The .bin (binary) and .hex (hexadecimal) are the same program, just different formats. You also set fuses through programmer. Once you make fusebit doctor, you can set fuses with it. I’m not much of an arduino man, but there are sketches to program microcontrollers.

  41. thanks alot Russel for the info i will look into it, for what i understand i will need to use avrdude burn the fuses and flash the hex file into it, maybe i can use arduino has a isp or use a usBasp to do it, i was asking cause i found this tutorial using a fuse doctor on breadboard and there its a scketch to use on arduino ino file

    apreciate all the help mate

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