Hello, I did 5 model board with the DM8168,The 1V_AVS power using TPS40400 chip, output 0.99V.Currently both the power supply board or the power requirements of the order are in line DM8168, but when power up the board, my SD card on the board sometimes start, sometimes it will not start, USART port does not print any information, and when it is seted to NandFlash start up first, is the samesituation! I have the power to fly to the EVM board of Ti, EVM board each time you open all the normal, very stable! Power problems should be excluded. I Would like to ask, if there are any factors affecting the chip enable those which that i need to pay attention? Which aspects of this large number? Thanks
Hello,
So do you mean that you confirmed that it is following the correct power up sequence?
Can you please provide any output logs you see on the UART output?
Regards,Marc
Please mark this Forum post as answered via the Verify Answer button below if it helps answer your question. Thanks!
Thanks for your reply! I have checked the power up sequence !And it does meet the requirement! But there is not any message output on the UART when turn on the switch of power for DM8168 !and then i checked the DDR3 clock,it is also not output,I checked the Pin of SD card power enable(U4)at the same time,this pin is also keep in low level ! But sometimes the chip could boot up correctly,the DDR3 clock and the Pin of U4 are all right!and the message is printed on the UART just like the EVM board! So i am confused with this condition!
and another question is :If the power does not meet the sequence requirements,DM8168 chip's internal logic would be damaged?
Yes.
Hi ,there is another question:the implementation of SmartReflex AVS is necessary or just recommended? does it can affect the chip boot up? Thanks!
It will not affect chip bootup, but AVS is required for correct chip operation.
HI~~~Lin, have you solved the problem?I made a board as the TI DM8168 EVM sch(version G). I meet the same situation as you, the power sequence goes fine, but there is no output when power up. Do you have some suggestion? Does anybody have some idea?
We meet the similar problem here. There are some boards can't finish the boot process. The power sequence is in line with the datasheet. The tracing register 0x4031D040h shows a value of 0x6. It means the ROM boot code can't reach the 2nd stage boot process. And if we connect to the A8 core using CCS and use assembly step to debug, it would loop in below 3 instructions：
00021abe: 1570F8D0 LDRNEB PC, [R0, #--2256]!
00021ac2: 3F40F411 SWICC #4256785
00021ac6: 4809D1FA STMMIED R9, {R1, R3, R4, R5, R6, R7, R8, R12, R14, PC}
Anyone can shed some light here? We are stuck in for a long time.
Please check the AVS output from very beginning of power up, it shall be set higher (about 1.2V) instead of 0.9V for normal boo-up and then can be lowered down later according to application needs by using the PMBus commands through registers of VOUT_TRIM, VOUT_MARGIN_HIGH and VOUT_MARGIN_LOW.
Thanks!
Phil