Hi @Davidino
Thanks a lot for your patience.
Regarding, What is the HI-Level and LO-Level voltage of that pin? Is it like as a normal gpio input pin (LO=0.3xV and HI = 0.7xV)?
For the RT106x the power group or supply rail is VDD_SNVS_IN.
Currently, there is no official documentation stating this. But we can refer to the below section of Table 22. Single voltage GPIO DC parameters from RT1064 Datasheet.
We need to substite NVCC_XXXX by VDD_SNVS_IN. An use case scenario would be:
if VDD_SNVS_IN is 3.3,
VIH = 3.3 x .07
VIL = 3.3 x 0.3.
Regarding : Is it possible to disable the internal pull-up resistor? I've tried disabling it but it doesn't seem to have any effect.
You need to set POR_PULL_TYPE to 0b01, by SW.
To verify this in your system you need to measure the current in VDD_SNVS_IN. Measure the current in scenarios 1, 3, and 5.
1) Press reset button , assering POR_B low. ( 19uA in my case)
2) Set set POR_PULL_TYPE to 0b01 after initializing GPIOs.
3) Press reset button , assering POR_B low. ( Current reduced to 10uA in my case)
4) Do a Power cycle.
5) 1 Press reset button , assering POR_B low. ( again I get 19uA in my case)
Important notes:
- We always recommend to use an external reset monitoring IC, even over external pull-up resistors. This reset IC provides a reliable way to ensure that the POR_B is deasserted after all rails are in steady state.
- I used RT1060 EVK to test, please verify in your RT1064 system.
- In our RT1060 disabling the pull-up does not seems to affect the MCU, no reset is generated. Probably is because of the external monitoring IC.
- I tested this by asserting POR_B or pressing the OpenSDA circuit's reset button. I saw that the a power cycle set the POR_B pull-up setting again.
- To give you better advise, please let us know more about your intendend system design for POR_B.
- To set the POR_PULL_TYPE with ease I halted the application just after initializing the GPIO, and I used MCUXpresso's Peripherals view to set the field to disable the pull-up. Then I stoped the debug session and I made a reset. If you want to do this in FW, you need to use a pointer to the related register.
All the best,
Diego
