Using Arduino Uno as a USB-TTL serial link to Casio FX-850P ?

[Dan C]

(07-21-2022 03:09 PM)Liam Hays Wrote:  Yes, it is possible. Upload an empty sketch to the Arduino (see below), and use the hardware TX and RX pins on the Arduino header. The empty sketch is to keep the ATmega chip from trying to also use the serial lines, freeing them up for your use.

As blackjetrock said, you should also verify the voltage level on the calculator. For example, my Casio fx-9750G PLUS uses 3.3V logic levels. Arduino Uno and most ATmega-based boards are 5V logic. The fx-850P port you pictured reminds me a lot of RS232, so you may need a MAX3232 or other RS232 converter.

Empty sketch (just to keep the ATmega busy):

Code:

void setup() {}
void loop() {}

What file transfer protocol does the 850P use? XModem?

OK, great!! Maybe it will work as i want then!
Hmmm, 3.3V or 5V logic levels in the FX-850P; i have no idea, have to look more on this.
But RS232 levels i think it's not, arent they +-12V? And the FX-850P has only 2 3V cells, so its max 6V if i understands it?