[Nolebrain]

Eshtaartha,

 

Thank you for such a quick reply!

We are still having trouble getting Linux to boot into Debian. At startup there is no CLK line signal on our SD card which makes it impossible to program the EEPROM through U-BOOT.

According to our schematic the SN74LVC buffer which is acting like a level shifter to drive WARMRSTN but was incorrectly pulled up with 1.8V. To fix this I added a 3.3V pull-up and a larger 100 uF capacitor to provide a very slow rise time (1.25 seconds). At startup ~ 10 mS after power is applied PMIC_PGOOD provides 1.8V to PWRONRTSN. In 1.25 seconds the capacitor is fully charged and WARMRSTN sees 3.3V. The LED then illuminates from SYS_VDD2_3.3V indicating a successful power up.

Here is a screenshot of the power up. CH1 (yellow) is the PWRONRSTN/PMIC_PGOOD (1.8V) signal. CH2 (blue) is the WARMRSTN (3.3V) signal. CH3 (pink) is the SD Cards CLK line. The CLK line is pulled up to 3.3V. In theory the SD CLK line should be pulsing around 120-150 kHz or greater.

https://imgur.com/gallery/BxZV7Kt

My question is why is the SD clock not running, if this runs we can insert a card and program the EEPROM with U-BOOT? We have a 24 MHz external oscillator attached to OSC0 which is working. I initially believed that the power up sequence was holding the AM335 in a perpetual reset. Is this not the case?

Due to the fact that the EEPROM is empty on our OSD335x-SM and we cannot get it to boot partially from the SD card, do you have another viable option? I read in the App notes that the device’s EEPROM could be programmed through USB from a host-PC or by external I2C programmer.

Any help is much appreciated. If you would like to speak directly I can provide contact info.

Thanks!

-NB

 

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