UART and Temperature at the same time MOD ATMega32

[Balze]

Hello all,

18 days ago Pawel added a picture and a little text to his github repository.

https://github.com/stawel/cheali-charger/tree/master/docs/temp_sensor/atmega32_mod

I would like to do exactly this, but don't know exactly what to do.

I see I should remove the 3.9k resistor.

I see a  ~40k resistor connected to one PCB trace and a second 3pin header.

What I son't see (and know):

Are pin 2 from both pin headers connected (that does not make sense, but I can't see it)?

Where doese the trace with the ~40k R go to? (Is it already pin10? Or...)

Do I have to use a wire to connect to pin 10 of the ATMega32?

What software-settings do I have to use?

Maybe someone [Pawel? :) ] can answer my questions. :D

Thanks in advance

Balze

[diggit]

Hi,

here is what's going on

Pink lines are new connections.

- in stock state, UART TX and external temperature sensor signals are connected together.

- Remove R2 (39k) to decouple UART TX from existing connector J1. It becomes dedicated temperature sensor connector.

- Add another connector to the other side of PCB (just for convenience, you can put is somewhere else) and connect GND and 5V pins to existing connector (5V is not necessary for UART, it mainly serves as mounting point of new connector J2.

- Connect UART TX using new resistor (R5) (just protection) to empty pin(2) of new connector J2. I suggest lower resistor value (100R ~ 470R is IMO fine), because some UART-USB converters have LEDs directly attached to RX line, putting too high load on so weakly driven line (when there is 39k resistor) causing signal integrity issues (basically no data received).

In charger menu:

Options->Settings->Uart->Output->Separ

Now, you should be able to receive charging data and use external temperature sensor simultaneously.

diggit

[Balze]

Hi diggit,

thanks you very much for clarification!

Now I see what makes my strugle.

In the schematics (Charger.pdf) there is no connetion to the TX line but a 3.9k R to GND.

Balze

[diggit]

No problem. I believe that's an error in schematic or it does not have shared connector.

diggit