How to transfer data through the audio jack?

Question

Microcontrollers

Hello. I'm interested in the question: I need to transfer information from the microcontroller through the audio jack to the computer. On the microcontroller, we get the output, but in order to get this data, you need to connect it to the microphone connector on the PC? Right? Or you can not connect to the microphone input. And just reprogram the audio connector on the PC to receive data. Is it really possible to do the same?
there was also an idea to add an SD memory card to the microcontroller so that all readings would be stored on it, at the end of taking readings, the data was sent to the computer. Tell me something? maybe I'm wrong about something...

Answer 1

Look at the modulations of older PCs that stored data on audio cassettes. Although it is strange to use the ancient MCS-51, SD card and audio transmission. Now there are normal AVR and STM with a USB controller, as well as ROM chips.

Answer 2

Everything has already been chewed out for you here: you make a modem on the FSK microcontroller, connect it to the microphone input on the computer and listen to the signal, after which you decode it. The driver didn’t fit in any way here, but you will have to write software for decoding the signal on your computer, of course. You don't need to "reprogram" the audio jack either, you already have a microphone input. It doesn't matter if it's single or combined.
If you don't want to have fun with encoding and decoding data - make a connection through the COM port, this is generally an easymode for beginners.
If you want through an SD card, learn how to work with it via SPI and work with the file system.
If your diploma is on fire and your knowledge of microcontrollers is in the vicinity of zero, do the exchange via the COM port and do not fuck your brain with headlines typed in caps, this is indecent.

Answer 3

unequivocally the second option "to add a microcontroller to a memory card" is better and more preferable since there are problems simply with getting sound, and therefore it is better not to even poke your head into the implementation of a sound FSK modem.
There are a lot of examples with a SD card. But since it is not indicated what you are doing, arduino / stm32, etc., then I can’t help. I advise you to google according to your platform. SD cards are utterly chewed, "I soldered 10 wires, copied the finished example and everything worked right away" such examples from the category are immediately available and you don’t know who to be in order not to find them.

Answer 4

LIKE THIS

Answer 5

Of course, you can encode 0/1 with different frequencies, but it is much more reliable to use USB

Answer 6

You can also use quadrature (2 phases) or tone (2 frequencies) modulation.