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PSoC 5, 3 & 1

Anonymous
Not applicable

Hi,

   

Specifications in the CY8CKIT-059 kit guide says the board works with 3.3V - 5 .5V from a regulated supply. I need to use the board with 3V supply. Is it possible to achieve with or without any modifications to the kit board? What restricts its usage with 3V?

   

Cheers,

   

Necdet

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20 Replies
rola_264706
Honored Contributor II

Power Supply System
The power supply system on this board is dependent on the source of the power. For most
applications, you can use the 5 V supply from the USB connection to power the system. You can
also connect an external power supply to the board
for low-voltage applications. The kit supports the
following connections:

5 V from the KitProg USB

5 V from the PSoC 5LP Target USB (this will not power the KitProg section of the board)

3.3V to 5.5V from a regulated supply connected
to VDD (this will not power the KitProg section of
the board)
Note:
In order to use an external power supply, while
KitProg is connected to the PCB USB, remove
diode, D1, from the board. This ensures that VTARG supply from KitProg is not supplied to the target
device. KitProg measures the target voltage and
adjusts the logic levels on the programming pins
accordingly.
It is important to understand that this prototyping kit does not have any onboard ESD protection
circuitry. Therefore, the power source for the PSoC 5LP Prototyping Kit must be of a high quality to
ensure that the board is protected from any over-current conditions and swapped-power connections.

   


I would look in to getting a buck boost power chip to raise the power back to 3.3 volts from the 3.0 volts you are using.

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Anonymous
Not applicable

Thanks for the input. I will consider boosting the voltage as last resort. The reason I asked is, the SoC operates between 1.71 to 5.5 V, but the kit's minimum voltage requirement is 3.3 V. Why is that? If it is because of some external components on the board that I won't be needing, I can just unsolder them.

   

BR,

   

Necdet

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WiFl_1166056
New Contributor II

I would also like an answer to this question about the CY8KIT-059.  Is there a reason to not regulate VTARG down to 3.0V (or even down to 1.71) connected to P5LP_VDD?   R20 is removed to separate VTARG from P5LP_VDD.

   

Thanks.

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Bob_Marlowe
Expert II

It is just a matter of programming. The output of the kitprog - part is 5V which will not be tolerated by a 3.3V driven PSoC target. On the other hand, when 3.3V peripherals are connected to the target device you may not program it with 5V.

   

Only way out I can see so far will be a level-shift interface for sda, sck and xres connections between snap-off part and prototype board.

   

 

   

Bob

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RaAl_264636
Contributor II

I don't think that it's neccessary to have level shifter if both parts use the same supply rather than have a special version of the Kitprog software which doesn't rely on 5V.

   

From a hardware point of view I think that down to 3.3V is possible (USB signals are 3.3V). Anything below makes USB and therefore the Kitprog useless, so that would be the point where separate voltage supplies are neccessary. Of course, in that case level shifting or open-drain mode is neccessary.

   

 

   

Regards,

   

 

   

Ralf

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Bob_Marlowe
Expert II

When you drive the target device with only 3.3V you will need a level-shifter between Kitprog and target, because the Kitprog signals are 5V. I cannot see yet how you will manage to run the Kitprog unmodified with 3.3V which would not need a level-shifter or isolation for connected 3.3V peripherals.

   

 

   

Bob

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WiFl_1166056
New Contributor II

I've confirmed that USB requires 3.3 (not 3.0) volts, as stated in the PSoC5LP Architecture TRM.

   

Everything I've read also confirms Bob's point that there should be a problem running the Target side of the CY8KIT-059 at 3.3V while the KitProg side is still at 5V. 

   

On the other hand, I've been running it this way for a month and haven't experienced any failures.  I'll deal with programmer voltages when we get closer to board design, or when it smokes; which ever comes first 😉

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Bob_Marlowe
Expert II

@Will

   

You will run into a problem when you connect to your -059 kit 3.3V peripherals which are connected to the board's Vcc. During Programming your peripherals will see 5V which might blow them up.

   

 

   

Smoking might damage your boards

   

Bob

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Anonymous
Not applicable

Hi Bob

   

please correct me if I m wrong.
I understood the kit 59 Manual that removing D1 cancels the 5V supply to VTARG and there for the KitProg can properly detect and adopt to the target voltage. As the KitProg is using SIO Pins as programming interface to the target I would guess SIO pins regulated output function is used to regulate down to VTARG !?

   

"...smoking might damage your board..." this depends on what I am smoking 😉

   

 

   

All the Best
Frank

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Bob_Marlowe
Expert II

I have never touched one of my boards with a soldering iron (yet).You can give it a try, I cross my fingers...

   

 

   

Bob

   

PS: Where in Germany are you located? I live near (more or less) Bremen.

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RaAl_264636
Contributor II

Hi,

   

 

   

sorry, maybe I was not precise enough: of course, the KitProg part also needs some modifications, at least a 5V-3.3V LDO or the possibility to only supply the port bank used for the debug pins with the target voltage. The latter one would be more flexible.

   

Unfortunately, the KitProg part of the circuit isn't prepared for designs using a supply other than 5V. So this renders all prototyping kits (-041/-042/-059) to 5V only designs. Even if the connection between MCU and KitProg is broken, a level shifter is needed. This something Cypress should take into account for the next prototyping kit (re-)designs.

   

 

   

Regards,

   

 

   

Ralf

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Anonymous
Not applicable

Hi Folks,

   

as I needed a quick solution for a 5lp on 3.3V I have removed D1, snapped of the Programmer and connected it to the programming port on the Kit-59. 
Power supply was done with 3.3V on the supply pins of the kit.

   

This combination is working perfectly. Programmer is detecting the voltage as it should and programming runs like a charm.
I also have tried the programmer on a 5V board and it worked.

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WiFl_1166056
New Contributor II

Bob,

   

Just to follow up on this thread; you were right.  The 5V programming/debug signals did damage the PSoC 5LP in subtle ways.  For me, everything worked except the USB wouldn't connect to the PC.  It only showed as "unknown device".   When I loaded the same code in an unmodified CY8CKIT-059, the USB worked fine.

   

To interface with the 3.3V I2C chips, I added a separate 3.3V regulator for the peripheral chips and the I2C lines are pulled-up to 3.3V. 

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Bob_Marlowe
Expert II

Thank you for keeping us informed, Will. I'd really like to see a new KitProg hardware that has got a selectable voltage for 3.3 and 5V operation.

   

 

   

Bob

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Anonymous
Not applicable

Hi Bob

   

Please correct me if I am wrong but I believe the KiProg on the Kit 059 is selecting the programming voltage according to the Target.
It only needs some minor modification for that:

   

 - Diode D1 needs to be removed, this cancels the connection from KitProg USB power to VTarg
​ - Target Board needs it's won power supply.
 - the prewired UART bewteen KitProg and Target needs to be cut. (I snapped the KitProg and made a 5 PIN connector)

   

The actual programming and debugging port is done via SIO Pins on KitProg. Those get referenced via VTarg which is (after D1 removed) Target voltage. 
I have running this modification here on my desk at the moment and seem to have no issues with it.

   

Did I miss some thing?

   

All the Best
Frank 
 

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Bob_Marlowe
Expert II

Frank, I have ~20 Cypress boards in my lab, not counting those I give away to interested people and I can assure you, I did not modify a single one, Partly because I am not as skillful as needed, partly because I am a bit hesitant to do so.

   

I'd like to see an answer from Cypress concerning that matter, which could mean that a simple modification as a jumper could make the kitprog more versatile.

   

 

   

Bob

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Anonymous
Not applicable

Hi Bob

   

Sorry for taking that long to come back... My normal (non electronics) commissioning job is a bit more demanding than expected this days 😉

   

You definetly have more boards in your lab than I have 😄  With this I am admitting that I am a little jealous on all the knowledge you have about PSoCs
I am pretty much a beginner in electronics and in PSoC but I have a bit further tested by now:
It works on PSOCs 4&5 powered from 2V to 5V (I did not try less than 2V)
As I asumed Cypressed used the SIO Pins for the SWD lines in so they can create Vref from the measured VTarg. I only can guess that they use VDAC to do so.
In any case the SWD lines on a scope show exactly VTarg as high level.

   

The only 3 (little) caveats I found so far:
1) Using the modified Kitprog's UART on Targets < 5V requires a level shifter. Direct connection will fry the Targets IO pins
2) If one wants to use a KIT 059 Target with <5V with it's USB then diode D2 has to be removed as it connects the Target to USB 5V
3) A Kitprog without D1 can not be used to power the target

   

Next will be to look into PSoC 3s but there I need to read some Datasheets / TRMs first how the programing interface is done. Have not touched the 3s till now.

   

See you around
Frank
P.S. any room we can meet and talk in german?

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dazi_1435086
New Contributor II
    

1) Using the modified Kitprog's UART on Targets < 5V requires a level shifter. Direct connection will fry the Targets IO pins

   
   

I wanted to add an update to this thread, since it's among the first search results for this topic.

   

I have a CY8CKIT-059 (looks like Rev 06) purchased recently. I have not snapped the board. I have updated the KitProg firmware to 2.17.

   

Because I needed to communicate with 3.3V I2C parts in my design, I removed D1 and powered the target with an external 3.3V LDO regulator (input to the regulator is from VBUS through a diode that I wired myself) I did not want to snap the board, as I have been using the KitProg UART for debug printing. I've been doing this with no issues so far, but I was concerned about damaging the target's I/O pins going forward.

   

I contacted Cypress and received the following response:

   
    

As you have rightly pointed out  with D1 removed the KitProg senses and adjusts voltage levels for programming the target using Special Input/Output (SIO) pins in PSoC 5LP.  SIO supports programmable output level and programmable input threshold. The logic is to sense the voltage level using ADC and adjust the SIO pin output.

    

We have also implemented similar functionality for UART and I2C pins internally. Thus there is no need of level shifter at these lines. Please let us know if you face any discrepancies. We tried to recreate the same and observed 3.3 V at SDA lines without level shifter. 

   
   

I put it on a scope and it does appear that both the TX and RX signals at pins 12.7 and 12.6 have 3.3V logic levels when the target is powered from 3.3V, the KitProg D1 is removed, and the KitProg is plugged into USB.

   

It sounds like this has changed from prior designs or firmware, so it bears checking in any individual case.

   

However, it appears it's okay for me to use the KitProg UART on my recently purchased unsnapped boards with 3.3V target power supply by simply removing the appropriate diodes.

   

Best,

   

Dan

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Bob_Marlowe
Expert II

Honestly: do not waste too much time on PSoC3. The CPU design is from 1980 and there have been a lot of improvements in technology since. The internal hardware as the components are the same as with PSoC5.

   

 

   

Bob

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Anonymous
Not applicable

Hi Bob

   

good point. will drop PSoC3 and concentrate on 4 & 5

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