SDIO bus to wilink8 emissions test

Rasmus Ahlberg

Hi,

We're about to do EMC emissions test for our product. The problem is generating traffic to and from the wilink8 chip, on the SDIO bus. We cannot connect to any router, so we can't send real IP traffic. I know we can use the PLT mode to generate send packet, but that's only from the chip to the antenna, right? Do you have any suggestions on how we can generate traffic on the SDIO bus? Currently our only solution is a loop continuously doing ifup on the wlan interface, but it feels like this won't load the bus much at all, compared to real IP traffic.

Regards,
Rasmus Ahlberg

over 11 years ago

0 Sundeep Javvaji over 11 years ago

TI__Mastermind 32615 points

Hi,

Could you please clarify why can not you connect to any router. Is it a restriction or you intend to do so?

how about the option of using wilink8 in AP mode with reduced beacon interval?

0 Rasmus Ahlberg over 11 years ago in reply to Sundeep Javvaji

Prodigy 170 points

Hi,
thanks for your reply.

It is a restriction, it would disrupt the emission measurements.

Do you know how low the interval be set? Can you set it to just a few ms? Then it might be an option.

0 Joseph Gigi over 11 years ago in reply to Rasmus Ahlberg

TI__Guru* 85400 points

Hi Rasmus,

Try 15 ms for beacon_int.

Regards,
Gigi Joseph.

0 Rasmus Ahlberg over 11 years ago in reply to Joseph Gigi

Prodigy 170 points

Hi,
By the way, the beacon interval isn't just configured in the chip and the broadcast generated there, it's actually generated in the driver using some timer?

Regards,
Rasmus Ahlberg

0 Joseph Gigi over 11 years ago in reply to Rasmus Ahlberg

TI__Guru* 85400 points

Hi,

You can find the definition in hostapd.conf

Regards,
Gigi Joseph.

0 Rasmus Ahlberg over 11 years ago in reply to Rasmus Ahlberg

Prodigy 170 points

Yes, but my question is whether this will generate traffic on the SDIO bus every 15 ms? I'd assume it's just a config value pushed down to the chip, but this is not the case?

Regards,
Rasmus Ahlberg

0 Joseph Gigi over 11 years ago in reply to Rasmus Ahlberg

TI__Guru* 85400 points

Hi Rasmus,

Yes, you are right. The beacon as such is generated by the chip. So there won't be any traffic on the SDIO bus.
I can think of two options for your case (other than the ifconfig wlan0 up/down which you already tried).

1. Set the AP beacon interval as 15ms, and start a scan (in loop) on wl8 - this should generate traffic on SDIO
2. The wl18xx test commands contains WL18XX_TEST_CMD_LOOPBACK_START & WL18XX_TEST_CMD_LOOPBACK_STOP - but they are not currenly mapped to any code. If you can add some code in the wl18xx_plt.c file, then this should be the best option for you.

Regards,
Gigi Joseph.

0 Rasmus Ahlberg over 11 years ago in reply to Joseph Gigi

Prodigy 170 points

Ah, OK. Thanks! The loopback command sounds promising, assuming I have the time to implement it.

Are there any parameters for the start command?

Regards,
Rasmus Ahlberg

0 Joseph Gigi over 11 years ago in reply to Rasmus Ahlberg

TI__Guru* 85400 points

AFAIK, no.

Regards,
Gigi Joseph

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SDIO bus to wilink8 emissions test