airzone:
serial data at 9600kbps.
[/quote= ??? kHz
mauried:
So the question what frequency is 9600 bps is meaningless.
So post # 18 is meaningless.
Those pulses have no frequency.
No, the pulses have many frequencies, not just 1 , and you cant measure it as its constantly changing.
Its a bit like asking what is the frequency of white noise.
On the drawing frequency is not changing but presence of the pulse, 0/1
Maybe it has meaning in a high school text book where they are trying to teach basic concepts of digital communications.
The 1's and 0's in USB are not +5v and 0v. There are no pulses. The difference in the D+ and D- voltages indicate the data. This is differential signalling. With single ended signalling - such as TTL, data is indicated by the presence or absence of voltage. I think you are confusing the two.
Maybe before you consider USB, check out the difference between RS232 and RS485. Conceptually similar, but RS485 uses LVDS. When you're ready for USB then, you can tackle the higher speed and protocol overheads.
i am talking about this
ted:
On the drawing frequency is not changing but presence of the pulse, 0/1
"Re: Serial1.begin(57600)"
If we go back to your original post (the title of this thread), then ..... the 57600 refers to serial communications signalling rate. And, to understand serial communications signalling rate, it's necessary to learn about serial communications.
As for your question about whether or not '57600' can be linked (somehow) to a measurable frequency........ then, yes..... it could be linked to 57.6 kHz ........ that's if you assume that the serial communications signalling rate is maintained (sustained).
And..... USB serial communications (itself) does not involve PSK.
If you are connecting a scope to a USB camera, you're not talking about that...
However if you are trying to read TTL serial communications on a scope, try How to read serial data from oscilloscope - Electrical Engineering Stack Exchange for a bit of guidance. You should be able to write up a program to loop writing a specific character to the serial port so that you can catch it for analysis. But only after you put the USB camera in a different room to the scope. lol
ted:
That's NRZI signaling (link in post #35) with a signalling period of 83.3 nanoseconds (post #21) from a USB full speed (12 MHz signalling rate) bus.
The confusion rises (at least) from not being clear about the distinction between signalling on the TTL serial bus (at the baud rate specified in Serial.begin()) and the signalling on the USB bus. They are not the same physical bus and do not run at the same rate. For a USB to serial converter the USB side runs at 12 MHz regardless of the TTL serial rate.
I don't see on oscilloscope 12 MHz on RX or Tx
ted:
I don't see on oscilloscope 12 MHz on RX or Tx
No indeed - you should see 12Mbaud, however.
It is ok, I understand what I see.