How can I measure CAN RX and ETH RX time?

Ferhat

Hello guys,

I have a AM335X GP EVM which I currently use for evaluation purposes. I need to determine the time, which is requiered to receive data. You can call this a kind of profiling. I need to do that for CAN and ETH.

How would you do such kind of measureing?

I thought about to measure the time of the appropriate ISR. I would trigger a digital output signal at the beginning and at the end of the ISR function, so I can use an oscilloscope to get precise time values.

Is there a better way?

Which digital output can I use?

I want to avoid i2c and spi.

Thanks

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi Ferhat,

What you propose is possible. You can use any available GPIO for this purpose.

0 Ferhat over 9 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Hello Biser,

Thank you for your answer. I tried to use GPIOs using this guide processors.wiki.ti.com/.../Linux_PSP_GPIO_Driver_Guide
For example I tried to set UART1 RX or TX to HIGH so I can measure with a multimeter a HIGH/LOW signal.
After bootup I connected to the device using UART0 to access the CLI via terminal.

I measured at PIN 33 and 35 of Expansion Connector EXP2 and directly at the DB9 connector (PIN 2 and 3). Switching with "echo 1 > /sys/class/gpio/..." and "echo 0 > /sys/class/gpio/..." didn't change anything.

For this purpose I switched to CPLD profile 7 and used GPIO0[14] and GPIO0[15]. Using the above commands.

Btw. I am a newbie. So maybe I am doing a simple stupid mistake. ;)

Thanks!

0 Biser Gatchev-XID over 9 years ago in reply to Ferhat

TI__Guru**** 393215 points

These are the necessary steps from user space:

Export the particular GPIO pin for user control. GPIO30 is taken as example: $ echo 30 > /sys/class/gpio/export

Change the GPIO pin direction to in/out: $ echo "out" > /sys/class/gpio/gpio30/direction

Change the value: $ echo 1 > /sys/class/gpio/gpio30/value or $ echo 0 > /sys/class/gpio/gpio30/value

However if you want to control the GPIO inside the ISR code you will need to directly set GPIO direction and value in the ISR code by writing to the GPIO registers, then recompile the kernel and run it.

Also, UART1 TXD/RXD pins are configured as UART1 pins in all GP EVM profiles. It's better to use for example GPMC_CSn1 and GPMC_CSn2 pins, which are configured to user LEDs 4 and 5 in most profiles.

0 Ferhat over 9 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Thank you. I am going to check GPMC_CSn1 and GPMC_CSn2.
So how do I trigger those using the CLI ? I would like to test them inside CLI without chaning the drivers.

Thanks!

0 Biser Gatchev-XID over 9 years ago in reply to Ferhat

TI__Guru**** 393215 points

I don't see how you can write to a GPIO register from within an ISR without changing the code.

0 Biser Gatchev-XID over 9 years ago in reply to Biser Gatchev-XID

TI__Guru**** 393215 points

Perhaps the Linux Trace Toolkit would be more useful for what you want to do: http://www.opersys.com/LTT/

0 Ferhat over 9 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Sorry I didn't write it correctly.
My first step would be to verify GPMC_CSn1 and GPMC_CSn2 in CLI if those really work. Like the GPIOs with "echo 1 > ...". and my multimeter.

So if I understood it correctly there is no way to test these in CLI (before changing my driver).
After that I am going to change the driver for the real measureing.

Thanks

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How can I measure CAN RX and ETH RX time?