UART Logic Levels


#1

Hello All,

I now know that the MangOH uses a 1.8V for a logic high. My question is what are the thresholds for it to receive a logic high and low. Is a high > 0.8V and a low < 0.2V acceptable or does it have some other threshold limits.

Thanks
Kas


#2

usually depends on the IC you are using.
A good thumb of rule (not always true) is 1.8*.3 = 0.54 as bandgap for the voltage.

So 0 to 0.54 V for logic low and (1.80-0.54) = 1.24V for logic high.

anyways, for safety sake you can say
0 to 0.4V for logic low
1.4V to 1.8V for logic high


#3

Is there somewhere to find this information for the module that ships with the MangOH Green board. I have looked at the data sheet but I can’t find anything specific to the serial data lines. The only info is on page 41 table 3-19. From that though I get a high is > 1.17V and a low is < 0.63V.

Kas


#4

Kas,

UART will be the same as any digital IO. So page 42 , table 3-19 shows you the relevant voltage levels.

cheers,
Ashish