When using mini-flex bus on MCF52259 - do I need to connect pull-up to D0-D7 ?

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

When using mini-flex bus on MCF52259 - do I need to connect pull-up to D0-D7 ?

Jump to solution
788 Views
ambre
Contributor I

Usually, pull-ups are needed on data bus, but in the MCF52259EVB schematic - no pull-ups are mentioned.

Labels (1)
1 Solution
513 Views
miduo
NXP Employee
NXP Employee

Typically, since the data lines can be inputs it is best not to have them floating at any time. However, we don't use pullups/downs on the data buses on our ColdFire eval boards.

View solution in original post

0 Kudos
4 Replies
514 Views
miduo
NXP Employee
NXP Employee

Typically, since the data lines can be inputs it is best not to have them floating at any time. However, we don't use pullups/downs on the data buses on our ColdFire eval boards.

0 Kudos
513 Views
TomE
Specialist II

Why do you think pullups are required on a data bus?

There are some instances in which this might be useful; I'm interested in your reasons.

Tom

0 Kudos
513 Views
ambre
Contributor I

Usually pull-ups are required on data bus, to make a legal voltage levels between access to the different devices on the bus.

Unless the devices on the data bus have internal pull-ups.

0 Kudos
513 Views
TomE
Specialist II

> legal voltage levels between access to the different devices on the bus.

Between accesses, no device cares what the levels are on the bus, so it doesn't really matter.

You haven't given me your specific reasons for wanting "legal voltage levels" between cycles.

Or why the EVB should be supporting and demonstrating that need or requirement.

Tom