I2C vs 5i22

Hi,
I try to write hal modul for communication with I2c device.
I connect SDA and SCL pins directly on 5i22, but there is big time delay between gpio IN and OUT pins.
I try wired gpio OUT to another gpio IN and generate signal by pwmgen and read this pins in halscope. Delay is same cca 0.01sec.
Is it normal?



thanks Martin

Note that you will not be able to view PWM outputs or other high speed outputs accurately
with halscope because halscope only samples the inputs at the servo (or base) thread rate.

This will cause aliasing so what halscope shows is not an accurate representation of the signal on the pin

en.wikipedia.org/wiki/Aliasing

Yes,
I know that the signal must have a small delay, but this delay is 0.01 sec.
Halscope sampling frequency is 20kHz and Hal modul for generating SDA and SCL signals pass through 4x-5x in this delta time
PWMgen frequency is setup only on 100Hz. Its linuxcnc pwmgen, not mesa pwmgen.
M

There is no significant delay in the GPIO driver or hardware so the delay
must be in your component logic somehow.

That is, if you set a GPIO pin, you can read it in the next cycle
(not the current cycle because with standard thread order writes are done after reads)

You can easily verify this by doing (something like) the following:

setp hm2_5i22.0.gpio.095.is_output true
net toggle95 hm2_5i22.0.gpio.095.in_not => hm2_5i22.0.gpio.095.out

This will toggle with a frequency of 1/2 the servo thread rate
(assuming the hm2 read and write functions are invoked at the servo thread rate)

Here's an example:

freeby.mesanet.com/toggle.png

I changed HM2_5i22.0read and write to base thread with fp and now its ok.
Thanks. M