questions about example program ex_usb_hid.c

[hemnath]

Hi,
I've been studying the USB and gone through the example code ex_usb_hid.c.

I have a question,
ADC on PIN AN0: Whether the ADC value will not exceed 255? If i want to send 1023, will it not send?

Thanks in advance.

[Ttelmah]

The example, configures the ADC for low accuracy only.
#device ADC=8

and

ADC_CLOCK_INTERNAL

This gives an 8bit low accuracy value.

No, you could not send 1023, The example PC code expects to only receive single bytes for simplicity/speed.

To send a larger value, the code at the PC end would need to be re-written to expect two bytes for each value, and the transmission code would have to switch the ADC to a more accurate mode, and send this as two bytes.

'HID' code is originally designed for things like joysticks (human interface devices), with the assumptions this brings.

[hemnath]

Thanks Ttelmah for the explanation.

[hemnath]

I'm asking in general, not considering this example.

This example sends 8 bit(1 byte) data in a single pipe. I'm clear about that.

Is it possible to send a 16 bit value through the single pipe?

Example:
out_data[0]=250; // It can be sent.

Will it be?
out_data[0]=1000;

Will USB allows 16 bit value?

[E_Blue]

No, USB sends only single bytes, that means 0 to 255 decimal values.
To send 16bit value you must two break the value in to two bytes and then put one byte on [0] and the other byte in [1]

Something like

[hemnath]

Thanks E_Blue..

What is Endpoint in USB?

Why there is maximum of 16 Endpoints.
Please clarify.