Using KitProg With A 3.3 Volt Target

The KitProg stub on the CY8Ckit-059 board is a 5 volt only board. But, with an interesting trick mentioned by the Cypress user EvPa_264126, you can modify the KitProg stub to work at 3 volts, and safely program 3.3 volt units. These modifications are more or less permanent.

Modification Choice #1

The trick is to replace the diode D1 with an LED. On the Infineon community board, this post describes using the board at lower voltages (you may have to register with Infineon to see this post):

If you can’t register, or don’t wish to, the image that the user published is here (shown under the fair use act):

Adjusting KitProg Board Voltage to 3V

How It Works

All LED’s (Light Emitting Diodes) essentially are Zeners that emit light. They take the current going through them and convert most of it to light. During the process, they also regulate the voltage across the LED to 2 volts. So, 5 volts in on VDBUS (the USB standard voltage) minus 2 volts for the LED gives you 3 volts to power the VTARG (and the programming voltage for the PSOC output).

The Possible Issues

Most LED’s are limited to about 30 milliamps before they overheat. Especially the ones you solder onto the board like this. Do not attempt to power your target board from this 3 Volt supply unless the current drain is within the LED tolerances. You could end up with a dead LED and a dead target. Why? LED’s usually short out when they burn up. 5 Volts – 0 Volts = 5 Volts == dead target board if it is not 5 volt tolerant.

Modification Choice #2

The second way to perform this action is to remove D1 altogether. Leave it off, and power the target from the voltage you desire. Either 3.3V or 5V. According to Cypress engineers, the KitProg firmware will adjust its voltages using the programmable I/O outputs to handle this:

Debugging PSOC5 with VSCode on Mac and Linux

Macintosh: take a look at my earlier posts here: and here: For Linux, All the information in those posts apply, along with my rambling.


Enjoy using your KitProg (version 1) with a 3 Volt target!

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