Trim output

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Anonymous
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I am controlling the Duty cycle of PWM output using the API given.. and its working fine, but the problem is with the amplitude.. i am expecting it arnd 3.3V (digital-3.3 & analo-5V).. but i am getting around 5V even after using a didital o/p pin.

   

What might be the reason behind this behavior?

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25 Replies
Anonymous
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        Hi bib, Tell me, Vddd voltage in system operating conditions, and output drive mode? When you upload your project, you can get more precise answer.   
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Anonymous
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There are 4 VDD at the 4 corners of the chip, each for different quarduan and ports. Check if you apply the right voltage to thoe pins.

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Anonymous
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        Regarding usage of output pins and CMOS level voltage, This article and pdf might be help. [ http://www.cypress.com/?rID=40989 ] - [ http://www.cypress.com/?docID=43941 ]   
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Anonymous
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 Hi,

   

I was going through the application none AN58304 for selection of analog pins .. well, to my wonder i have always used Port 3 for digital purpose too.. and never observed ny irregularity. now when i am observing the trim voltage level i am observing irregular behaviour. All the four vdd voltage is set to 5v.

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Anonymous
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This application note recommends that we should use Port3 and Port0 for analog purposes.

   

But I thought these were GPIOs and can be configured as both analog or digital [as per our need].

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Anonymous
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 exactly... thats what i am saying.. how much SNR ratio will be effected if are using the analog pin for digital purpose?

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Bob_Marlowe
Level 10
Level 10
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All (most) of the pind are General Purpose IO. The recommendation to use Port 0 and 3 for analog purposes has to do with the chip-internal wiring and can assure that distortions cross-talked from digital lines to the analog signals are minimized.

   

So, feel free to use the pins as you like to and keep in mind that just for high-precision ( > 16 bit) some more thoughts regarding noise immunity, precision and stability have to be made.

   

 

   

Bob

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Anonymous
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May be I missed something here. You have all VDD to 5V, would this means the output should be 5V and not 3.3V?

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Anonymous
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 according to my jumper settings... digital should be 3.3 and analog should be 5!!! 

   

do we need to change the '.cydwr' -> system -> operating conditions too??

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Anonymous
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        bib, You must listen to the answer and must read the document carefully. And you must replay to what whom said. When your Vddio is 5v, you can't get CMOS level output. IF you want to interface with CMOS devices partly, and or other voltage devices partly. And still you want to use Vdd as 5V for PSoC. You have to use SIO pins (port12) and Select the Drive Level to Vref. OK??   
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Anonymous
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I never checked it out before...

   

On my PSoC kit, I have configured my jumper settings as : 3.3 digital, 5V analog.

   

After this, if I am working on PSoC Creator and if I go to : ProjectName.cydwr -> Systems, all four VDDD are configured as 5volts.

   

So if I try to programme this project, do I need to change these VDDD values to 3.3V.

   

Regards.

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Anonymous
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        It is sorry, I'm not sure of separation issue of VDD, VCC, Vddio,Vdda ... HaHa. At first, Set actual voltage to VDD=Vdda=5 and Vdio1,2,3,4= 3,3 and try again. Maybe it will be work.   
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Anonymous
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 and to sum it up... I was exactly asking what you are not sure of 🙂 can anyone please tell me how it works??

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Anonymous
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 @goose: what kit are you using?

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Anonymous
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@PSoC73.....I am asking in general......

   

If, my jumper settings say VDDD = 3.3Volts...

   

But .cydwr ->system say VDDD = 5volts...

   

 

   

Which one would take preference over the other?

   

Regards.

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Anonymous
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        As you say ”jumper settings say VDDD = 3.3Volts..." Are you using what kind of KIT? Maybe 010 and 050. I am not using it. but ok. "cydwr ->system say VDDD = 5volts..." I presume that is only just a COMMENT. Actual voltage is so, PSoC work so. Is Someone help us.   
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Anonymous
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1. The setting in the  .cydwr file should be set to the same as the voltage applied to the 4 Vdd.

   

2. You should be able to locate the circuit diagram for the kit and check what voltage is applied to the 4Vdds. or just tell us the kit you are using, People here may be able to check that for you as well.

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Anonymous
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        I am using CY8C3866AXI-030 kit. This is really confusing. The PSoC 3 datesheet suggests to have the following jumper settings : For 5v Analog , 3.3 Digital : J11-3 to J11-2 && J10-2 to J10-1. This is exactly what I have always done. BUT I have never changed the values on the .cydwr -> system page. This page shows all the four VDDDs to be 5V.   
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Anonymous
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The setting in the cydwr is to be change by the USER. You should change it to the same as the voltage applied to the VDD pins.

   

I think it changes some internal setting for I/Os but not 100% sure. May be thershold for inputs or some internal configuration for output pins. 

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Anonymous
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I don't have the kit you use, bu you should be able to find the circuit diagram with the kit or from the CD. That should show you what is actaully connected to the VDD pins.

   

May be some one here who has the kit be able to help.

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Anonymous
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        I am confused. Looks like two member have the same problem.   
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ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

Most kits with jumpers for setting Power rails are setting actual HW,

   

like selecting which regulator, setting G resistors to set regulator output

   

V........

   

 

   

When you set in Creator the voltage you are telling code base what HW

   

voltages are going to be present when PSOC is run. Stated another way

   

settings in Creator do not mean processor starts up and sets its own

   

primary rail supply. "Primary" because there are regulators in PSOC 3 / 5,

   

working off the externally supplied power voltages.

   

 

   

So in short both settings in Creator and HW on board must match.

   

 

   

PSOC 3 power -

   

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Anonymous
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Dear Dana you said :

   

"So in short both settings in Creator and HW on board must match."

   

 

   

Suppose they are different, which one would take preference over the other?

   

[I think it should be the HW one...ryt!!!]

   

Regards.

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Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

The specifications given to Creator regarding the voltages are used to INFORM the chip about the outer world. As Dana told they are related to internal switching and settings and do not change any input-voltages. So they do not govern anything but are needed for internal calculations as stabilizing the oscillators and regulators.

   

 

   

Bob

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Anonymous
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 Now that clears my doubt.. Thank you all 🙂

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