kl25z VLPS Mode Wake Up

[asdasdaram]

Hello, im using 8.4.2 Example 2: Functionality of UART0 in VLPS mode . That Example is in KLQRUG Peripheral Module user guide. I can enter the VLPS Mode with writing an 'e' at the terminal but then the uart expects 0x81 or 0xAA to wake up from VLPS. How i can send that with the keyboard. And in VLPS mode the Power consumption is 5 mA. its too much. The Data Sheet says 16 µA at 25* Celsius. How i could wake up from that with the UART.Maybe someone has another example?.

I tried the Low Power demo example and measured the Current. The Consumption of VLPR at 4 MHz for instance is 2.3 mA. It should be less a mA i think?? Whats wrong with it.

Thanks for Help and Tipps.

[santiago_lopez]

Hi Aram,

I don´t think you can send a 0x81 or 0xAA with the keyboard. For those cases I use a software named RealTerm (Terminal Software). This is a terminal emulator that allows you to send characters formatted in hex.

If your board is consuming 5mA probably it is not entering in VLPS. I have had experiences with some Kinetis K MCUs where the microcontroller does not enter to VLPS if you are debugging. What you need to do is load the program in flash, then disconnect the power from the board and connect it again. After that the MCU should be capable to enter VLPS.

Regarding the VLPR, many things can be causing the overconsumption. One is if you have a debugger connected (it can make the MCU consume around 1mA more). Other could be if you are enabling the internal FLL or PLL (if present) to increase the clock frequency. See how many modules you have enabled that can be consuming some extra current.

[asdasdaram]

ok i try RealTerm. I use Terra Term for now. You are right that VLPS sometimes cannot be entered, so i had to reconnect the power, even reset didnt helped.

I power the Freedom Board from USB and measure the current only on the Mikrocontroller not on the Debugger. Tthe Board has  a header J4 where u only measure the Microcontroller Current. http://www.freescale.com/files/soft_dev_tools/hardware_tools/schematics/FRDM-KL25Z_SCH.pdf . the Clock is off in VLPS there is only 4 MHz for UART on.