i.MX535 Boot Mode

[SrideviK]

Hi,

I am using i.MX535 processor in my design.

The boot mode pin configuration is as per the attachment.

When the switch is closed, then serial boot mode is entered.

When the switch is open, internal boot mode (eMMC) is entered.

This configuration happens properly.

In a fresh device, the eMMC is not programmed at all and the switch is placed in internal boot mode.

Then as per the boot sequence, since there is no boot image in eMMC, there will be boot failure and the processor has to enter the serial downloader mode.

Am expecting that the MFG Tool should detect the device for serial download. Pls clarify whether this will happen or not?

[igorpadykov]

Hi Sridevi

yes this understanding is correct, in particular it is described in

IMX53RM  sect.7.2.5 Mode: Serial Downloader (BOOT_MODE[1:0] = 0b11)

The serial downloader is invoked if the external Flash device is not programmed, when a

failure is encountered during the boot flow process

After entering the serial downloader, MFG Tool should detect the device.

Best regards

igor

[SrideviK]

Hi Igor,

Thanks for the reply.

BOOT_MODE[1:0] = 0b00 & other bootstraps are made for eMMC boot in my case. The boot switch is not populated in hardware.

Since as you said rightly, there is no image in eMMC (in fresh device) & the device has to enter Serial download mode. So MFG Tool should detect the device.

But this is not happening in my device. Pls advice where could be the problem.

Regards,

Sridevi

[igorpadykov]

Hi Sridevi

from sect.7.2.5 Mode: Serial Downloader:

To determine the active serial port, either UART or USB, the processor ROM program

polls the UART and USB status register for approximately 32 seconds. If there is no

activity on either port within the predefined polling time, then the ROM program will

power down the SoC using Watchdog Timer (WDOG-1). When the serial bootloader is

active WDOG-1 is reset periodically. If the communication between the serial Host and

the i.MX53 is idle for more than 32 seconds or the processor goes into an endless loop,

then WDOG-1 expires and powers down the device.

Also such behavior "device has to enter Serial download mode" - is applicable

only to iROM boot flow, that is when code is implemented by iROM itself.

If for example, iROM boots from eMMC, copies code to DDR, then jumps to DDR

and hangs there - this already is not iROM code. This case should be handled by

customer application code.

Best regards

igor