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
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
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
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.
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.
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.
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.
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.
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.
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 ;-)
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
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
I have never touched one of my boards with a soldering iron (yet).You can give it a try, I cross my fingers...
PS: Where in Germany are you located? I live near (more or less) Bremen.
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.
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.
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.
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.