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am335x staterkit

Other Parts Discussed in Thread: SN74AVC4T245, AM3359, WL1271

Hai

  I referred am335x EVM kit,am335x starter kit .In both the EVM has a Wifi module such as Murata.

In those schematics,the wifi modules were connected through the Buffer IC SN74AVC4T245 (4-bit voltage translator) towards the host processor.

But i referred one chinese product DEVKIT,They were also using am3359 host processor embed with wifi module (murata with same chipset WL1271L) without using any BUFFER ICs.

I took the design mostly from TI EVM kits,TI designers prefer that buffer ICs but in chinese make they were not.

It makes my doubt stronger.......What can i do in my board?????I'm using JORJIN module WG7311-0A(chipset-WL1271L

My reference kit is am335x starter kit.

  • Hi Rajas,
     
    These voltage translators are necessary because the WiFi module's I/O voltage is 1.8V and the processor's I/O voltage is 3.3V. What you can do is check if this chinese DEVKIT has the WiFi module's I/O voltage at 3.3V, or the processor's I/O voltage at 1.8V. The same is valid for your Jorjin module. As the Starter Kit has I/O voltage of 3.3V, you can check if the Jorjin module supports 3.3V I/O voltage.
  • Hi Biser,

    can you confirm, that AM335x Starter Kit's (TMDSSK3358) WLAN module (wl1271l) operates at 1.8V? And hence MMC signals like MMC1_CMD have pull-ups to 1.8V?

    Linux source code says

    static void mmc1_wl12xx_init(int evm_id, int profile)
    {
            setup_pin_mux(mmc1_common_pin_mux);
            am335x_mmc[1].mmc = 2;
            am335x_mmc[1].name = "wl1271";
            am335x_mmc[1].caps = MMC_CAP_4_BIT_DATA | MMC_CAP_POWER_OFF_CARD;
            am335x_mmc[1].nonremovable = true;
            am335x_mmc[1].gpio_cd = -EINVAL;
            am335x_mmc[1].gpio_wp = -EINVAL;
            am335x_mmc[1].ocr_mask = MMC_VDD_32_33 | MMC_VDD_33_34; /* 3V3 */
    }

    During boot I see following message:

    [    1.809814] mmc1: card claims to support voltages below the defined range. These will be ignored.
    [    1.830780] mmc1: queuing unknown CIS tuple 0x91 (3 bytes)
    [    1.838287] mmc1: new SDIO card at address 0001

    Where in the code the voltage of the MMC1 will be set? The ocr_mask seems to be only used for capabilities comparison. Am I missing something?

    Yegor

  • Hi Yegor,
     
    Yes, I confirm that the WLAN module on the Starter Kit operates at 1.8V. MMC1 signals are on the VDDSHV1 domain, which is also powered from 1.8V. The rest of the WLAN signals are routed through level translators. The Starter Kit schematics can be found at: http://processors.wiki.ti.com/index.php/AM335x_StarterKit_Board_Design_Files