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USB Low-Full-High Speed Peripherals

Anonymous
Not applicable

 Hi,

   

Which is active level  of data bus should be? 1 V is ok?

   

Regards, Roman.

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9 Replies
Anonymous
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 I'm not sure if you're talking about Voh, Vol, Vih or Vil. Please look at page 38 of the datasheet. It has all the values tabulated.

   

http://www.cypress.com/?rID=38801

   

Regards,

   

Anand

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Anonymous
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 Ok,  thanks.

   

One  more qustion. Do i need to pull up data bus?

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Anonymous
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        Can you please briefly explain you application? Are you using FX2Lp in slave of GPIF master mode? The 8/16 parallel data do not need any pull ups.   
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Anonymous
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 NIKL, i' m using GPIF Master mode.  CY7C68013A coonected with that microchip: http://www.holtic.com/products/2992-hi-3582a-hi-3583a.aspx via data bus. The problem is when data  set up i can't see enough voltage level on data bus (it's about 1 V). And i'm using GPIF Designer utility to create GPIF waveform.

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Anonymous
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 The link that you gave talks about 37.5 ohm series output impedance. The voltage levels specified in the datasheet are at 4mA current drive
1. Please check the current being driven by FX2LP

   

2. The link you gave talks about ARINC 429 serial bus and impedance matching to 37.5 ohms. Please clarify on this. Looks like the chip is assuming it is talking to a ARINC 429 device and expecting a 37.5 ohm resistance line. Which is not the case with FX2LP output.

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Anonymous
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aasi, i guess you misunderstood that. 37.5 Ohm is not on data bus, it's on ARINC serial output.

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Anonymous
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My problem changed a little bit. On some data bus pin is about 2.4 V voltage level, on other 2V, that is not enough in my application. Why so?

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Anonymous
Not applicable

 The values in the datasheet for Voh for an Iout of 4mA is 2.4V.

   

FX2LP should be able to drive inputs comfortably assuming the input impedance isn't very low. That is the reason I'm asking you to measure the current being driven by FX2LP.

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Anonymous
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Problem solved. In my case just CY7C68013A write data and the same time microchip try to read this data. So there is low active level. Thanks for helping.

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