first bootlet failure: power_prep on a customized imx28 board

[christianvieira]

We are a brazilian cia developing a new electronic payment system based on iMX28 processor. In our current custom board called, we has faced a problem into first stage of bootlet called power_prep. The message send to the debug serial is show above as reference:

HTLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLFLC
PowerPrep start initialize power...
Battery Voltage = 3.95V
5v source detected.Valid battery voltage detected.Booting from battery voltage

At this point, the processor reset and automatically restart, showing the same
message again and again.

Our schematic was based into the i.MX28 EVK PCB REV D and all voltages values would be seen ok when matched with freescale evaluation board.


Anyone has faced any similar problem?

Thanks in advance,

Christian Vieira

[Ramtry · Accepted solution]

Hi Christian,

Try apply the patches which given below. Hope this may fix your issue.

https://www.freescale.com/webapp/Download?colCode=L2.6.35_10.12_5V_SUPPLY_PATCH&appType=license&loca...

Thanks & Regards,

RAM

[christianvieira]

Hi Jorge!

I atached my schematic for your review! Thanks a lot for your time!
Because our custom board has in validation phase yet, we mount only:
imx28-pmu(page 1), imx28-psu/emi-bus (page 2), imx28-lcd_bus/gpmi (page 3)
imx28-ethernet/pwm/saif/usb/adc (page 4), imx28-spi-uart-can-i2c (page 5),
nand-flash (page 7), ddr2 (page 8), SSP-interface (page 11),
uart-interface (page 12), power-supply (page 23).

Note that we already made some changes in the schematics (but not update the document yet):
1). The PSWITCH and RESET circuit is now the same found in the MX28 EVK
2). I remove the C38 from my board (can be found in page 01)
3). The net PWRGATE_SSP0 found in the page 05 (imx28 pin D2) has connected now
    into the PWM3/GPIO3_28 (imx28 pin E9) -- This pin enable the power-supply
    of the MMC Card.
4). I changed the debug uart pins (nets uP_DUART_RX and uP_DUART_TX -- imx28 pins C7 and D8)
    to imx28 pins K7 and L7; like found in the MX28 EVK.
5). Change the value of R125 to 470kR like found in the MX28 EVK.

I've already check the boot-loader configuration mode that in my board can be done through
resistors (page 09).

In respect of reproduce the same error on MX28 EVK, the error not
happens and I use the same SD Card with the same "images" (imx-bootlets+linux image).

Thanks,

Christian


Jorge Ramírez Rivero said:

Hi Cristian,

Never seen this problem, but may I offer to help you by checking your schematics for possible issues? Are you able to reproduce it in the MX28 EVK?

Best regards.

Jorge.

[christianvieira]

Hello Marco!

Thanks for share your knowledge, but in my case seen to be very strange once my voltages are:

Main voltage (5.0V): +5.03V (coming from 24VDC, passed through a DC/DC step-down: LM5576)

Main voltage (3.30V): 3.28V (coming from 5.03V, passed through a LDO regulator: LD3900)

Battery (LiIon) voltage: 3.95V

PMU voltages:

DCDC_VDDIO: 3.25V

DCDC_VDDA: 1.87V

DCDC_VDDD: 1.198V

Marco Catellani said:

I've encountered a similar issue.
In my case the main voltage was 4,6V instead of 5V.
The internal switching of the imx28 can't work with a voltage minor of 4,7V. If this happens the i.mx28 will block inesorably.
I've tryed to modify the Brownout threashold of the 5V, I've tryed to set it to 4,4V, but the problem remain.
I've resolved modifying the 5V.

[katte]

I've encountered a similar issue.
In my case the main voltage was 4,6V instead of 5V.
The internal switching of the imx28 can't work with a voltage minor of 4,7V. If this happens the i.mx28 will block inesorably.
I've tryed to modify the Brownout threashold of the 5V, I've tryed to set it to 4,4V, but the problem remain.
I've resolved modifying the 5V.

[JorgeRama_rezRi]

Hi Cristian,

Never seen this problem, but may I offer to help you by checking your schematics for possible issues? Are you able to reproduce it in the MX28 EVK?

Best regards.

Jorge.