My broken 15 y/o w/m has a serial port tracing to an
atmega32L chip.
I have a USB to TTL adapter
which is set for 5v (as opposed to 3.3v) using a jumper. The TX,
RX pins are connected to the RX, TX pins of the w/m, respectively.
The power supply pins (0v & 5v) are left disconnected.
I ran minicom -D /dev/ttyUSB0 -b 9600 on the PC with the w/m
powered off. Minicom seems to default to an “8,N,1”
configuration. When I power on the w/m, minicom flashes a popup
saying something like “no connection to /dev/ttyUSB0”. This is a bit
bizarre because if powering the w/m triggers that popup, obviously
there is a connection of some kind.
I do not have the service manual for the Beko WMD 26125 T and the
mfr “lost” their copy. I have only scraps of service docs for a
similar model that were leaked to a shitty manual jailing
service. The circuit diagram of these docs label the serial port as
“EEPROM” (as pictured). I suspect the ISP port is strictly for
flashing (programming) the machine while the serial port is
apparently for accessing the storage (to see the error state that is
stored and perhaps clear it if I am lucky).
The goal is to confirm that the error code is “5” (my guesswork
based on LEDs lit in binary [101]). The ultimate goal is to clear
this fucking error off so I can use the machine. All components work
when hotwired (motor, pump, inlet valves). I believe the error state
is the machine caught in a lie. Normally the error states are
cleared by pressing a secret button sequence, which the mfr witholds
from the owners so they can charge us hundreds to do simple repairs.
What can I do without help from the manufacturer? Am I left with
trying different baud rates and configs? What should I try? The
w/m software is obviously a closed source, thus the serial config is
kept secret from w/m “owners”.
Anti-repair rumor: manufacturers disable serial ports before
shipping to block repair. But that practice may have started after
my w/m was made ~15 yrs ago.
https://www.alldatasheet.com/datasheet-pdf/pdf/77391/ATMEL/ATMEGA32L.html
Check for VCC and AVCC voltage when the washing machine is on. I expect it to use it's internal clock, so it will be wired through a low pass filter on the board.
I’m trying to get a handle on what VCC and AVCC is. This thread gives some chatter on it but I’m still not correlating this to the TTL port.
https://overflow.manganiello.tech/exchange/electronics/questions/86207/atmega8-why-do-vcc-and-avcc-have-to-be-connected
They are talking about digital analog conversions with port C (and I think the eeprom serial port i am trying to talk to is port D).
Linux and UART is my weekness, but I wondered why you added a Baud Rate and did some digging.
This thread might be helpful.
https://stackoverflow.com/questions/5347962/how-do-i-connect-to-a-terminal-to-a-serial-to-usb-device-on-ubuntu-10-10-maveri
Scrap the Baud rate and make sure you got the right permissions on /dev/ttyUSB0
I think they mean C for the clock (SCL) and D for the data (SDA) pin of the eeprom.
VCC is the power input of the microcontroller. Without Power, it wont work. AVCC is the power input of the ADC of the microcontroller. You still want to power it, even when unsused. You're connecting it directly to the VCC because it is desired to be exactly the same voltage. If not, the microcontroller likely wont work or act up.
In your case it's very likely the ADC is used as an internal clock, so you definitely need AVCC, but it's 99% likely that it's already connected as you need.