Albert Arquer

mx25 iomuxing

Discussion created by Albert Arquer on Oct 10, 2011

Hi, I have recently been using the IO Muxing tool probided by freescale to try and sort out the pin muxing scheme.

My question is the following.


In our design we would like to use as many GPIO pins as possible but we still need a SDRAM, a Nand Flash, a USB Host and OTG ports, a SDHC channel, and some others. In the IO Muxing utility I get warnings telling me tat not al GPIOX pins are operated at the same voltage strength (the tools says "Check power settings for CRM, EIM, JTAG, LCDC, MISC") and I can see that some of the pins that I am using as GPIO are beeing operated and 1.8V and some others at 3.3V.

My question is how can I fix this problem? I mean, it is not like I can change the supply for the EIM modules from 1.8V to 3.3V and be done right? wouldn't that damage the SDRAM?


I know I must sound pretty stupid but the truth is that i don't really understand the problem to begin with, I have been looking at the chapter on IO muxing from the reference guide over and over and I still don't get it.

I mean, I understand that some pads can not be operated at different voltages and must all use the same one but why is that really a problem? I mean, If i know this, and i place the right logic translation circuitry in my board will I have any problems?


One of the things that I don't understand from the reference guide is for example what is said on page 4-11 when talking about the SW_PAD_CTL_GRP_DVS. The last words on the first paragraph are "DVS control is only valid for GPIO pins." but then if you look at table 4-7 where you have a description of all the grups that allow DVS configuration you see all sorts of modules!!! not only GPIO pins....


I would really appreciate if someone could shine some light over this....

Original Attachment has been moved to: 640-IOMuxing.xml