i.MX6 BT_CFG from GPIO not working

[jaydcarlson]

I have a custom i.MX6-based design I'm bringing up with both MicroSD (on SDHC3) and eMMC (on SDHC1). I'm trying to boot from MicroSD right now. I've broken out the BT_CFG pins, and I'd like to set the boot config using GPIO pins.

Unfortunately, the i.MX6 always jumps to the USB serial download, no matter what settings I use on the BOOT_MODE[1:0] pins or the GPIO BT_CFG pins.

I've verified the correct voltages at the DIP switch used to set the boot mode, and I've tried it both from a cold boot, and by resetting the i.MX6 by pulling POR low -- either way, it jumps straight to USB serial download. I've verified the MicroSD card has a boot image that my RIoTBoard has no problems booting from.

Any ideas?

Here's my schematic:

[vacer-chen]

I met the same problem :smileysad: , can you tell me the solution ??

[Yuri]

Hello,

1.

  Please check SRC_SBMR1 register of the i.MX6 (with a JTAG debugger)

“The Boot Mode register (SBMR) contains bits that reflect the status of Boot
Mode Pins of the chip.”

2.
Please verify if any SD accesses are provided during boot.

Have a great day,
Yuri

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[jaydcarlson]

1. SRC_SBMR1 has a value of 0x3040. BOOT_CFG1 = 0x40 indicates that SD/eSD is selected (with all default options: regular boot, normal SD speed, no power cycle, and internal loopback clock source). Boot_CFG2 = 0x30 indicates all default options other than enabling 4-bit bus width

2. I put a scope probe on the SD_CMD pin, and it wiggles around a bit when power is applied.

After looking at the suggested signals, it looks like it's trying to boot from MicroSD card, but can't?

I'm looking at hardware issues:

I didn't put any pull-up resistors on the SD card's pins, as I thought I read somewhere they were internally pulled-up. Is this not true?

I only have 1 uF of decoupling on the SD card connector. I bumped it up to 22 uF by hanging a thru-hole electrolytic off the board by the connector, and that didn't change anything. Not sure if I need more.

Thanks!