USB REsistors - location confirmation

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Hey all.

 

I am using a Silicon Labs cp2102n USB to uart bridge and in reading the datasheets and application notes there is no mention of putting series resistors on the D+ and D- lines.

 

I am assuming that the reason for this is because this is not a HOST controller, but an end device. 

 

So for my own sanity be fore I send out the boards and I correct?

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Looks that way:

 

CP2102N Features

 

--Mike

 

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Thanks Mike.

 

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign wrote:
I am assuming that the reason for this is because this is not a HOST controller, but an end device.    So for my own sanity be fore I send out the boards and I correct?
It might seem like nitpicking, but your assumption is false. The resistors you mention are the termination resistors of an impedance controlled transmission line and they are needed on both ends of the cable, just like with coax, Ethernet, RS485, LVDS, SATA, etc and any other high speed bus. The reason the datasheet of this prolific chip states " No EXTERNAL resistors required" is because the resistors (or something similar) are built into the chip itself.

https://duckduckgo.com/html?q=usb+termination+resistors

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

Last Edited: Thu. Jan 31, 2019 - 07:14 PM
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Great input Paul!

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user