How do to set to let iMX258 into Stop mode ?
I have try to set Clock Control register(CCTL) and LP CTL fleid to 11 and then measured the current consumption .
It have been reduced to 25mA. (I have removed other peripheral ICs.)
is it right ?
(*( unsigned long *) CCM_CCTL ) |= 0x03000000 ; // Stop mode
asm ("MCR p15, 0, r1, c7, c0, 4 \n\t" ) ; // WFI
Above should be fine. Make sure JTAG is not connected as it may prevent going to low power mode.
" JTAG is not connected as it may prevent going to low power mode." means I need to remove those pull-up and pull-down resistors, is it right ?
No, it means that you shouldn't have JTAG probe connected and initialized for debug of i.MX25.
For reducing power consumption, make sure modules that are not used are disabled and clocks to it gated. Memory needs to be put so self-refresh mode as well.
Thanks a lot.
I still do reducing current consumption to under 6mA for stop mode, but I can't achieve until I remove 3.3V power .
Can 3.3V power be removed under stop mode ?
No, I don't think it's good to remove those voltages. What is the value of OSC24M_DOWN in PMCR2? Please also check detailed description of entering STOP mode in Chapter 15.4.3.2.4 of i.MX25 ref. manual.
Thank you ,
But I have a problem . The PMIC that I used can't change to 1.0V , means is it can't into stop mode ?
or If 3.3V is removed under stop mode , what are side effects ?
No, it does not mean that. i.MX25 will go to stop mode even if you don’t reduce voltage. Reducing voltage just reduces even further leakage current in STOP mode.
Datasheet specifies what are the required voltages and whether it’s possible to disable them. Device behavior is not guaranteed if datasheet is not followed. I don’t think datasheet mentions you can remove those voltages.
Thank you very much.
If core voltage doesn't reduce to 1.0V , Have a idea for the leakage current that core voltage is 1.45V in stop mode ?
Sorry, I don’t have such information.
If only imx258 is on the board and let it into Stop mode , What is the current consumption , less than 30mA or ..... ?
Datasheet shows guaranteed minimal values possible to achieve over the temperature range supported for i.MX25. But real number will also depend on the system, how much current is leaked through GPIOs etc. So if you see higher current on certain power rail, please check how it’s GPIOs are configured and what might be causing higher consumption on that domain.
Vladan