3 Replies Latest reply on Feb 24, 2011 4:14 AM by udayanu_

    Logic Levels?

      I am a college student using the PSoC 5 FTK, and I am new to the PSoC (I come from a background of Arduino, BASIC, and C++) but I have spent the past two weeks here and there reading technical documents, watching video tutorials, and compiling example code to understand this device. I understand that the PSoC devices are a completely different animal than the AVR controllers used with Arduino. The problem is, I can't seem to find the logic levels the PSoC5 is capable of.

      I need to work with TTL (5V) levels. My understanding is that the PSoC uses 'LVTTL' which is 3.3V? Correct me here with either of these assumptions if I'm wrong. The project I'm trying to include the PSoC in must interface with an iRobot Roomba (robotic vacuum) 'ROI' (Roomba Open Interface; PDF here: [url]http://www.irobot.com/images/consumer/hacker/Roomba_SCI_Spec_Manual.pdf[/url])

      I have also tried to understand the FirstTouch Starter Kit power scheme (J1/J4 jumpers, Dddio, etc.) but to no avail. 

      I can't get anywhere without this knowledge so to anyone out there who can help, thank you!!!  

        • 1. Re: Logic Levels?

          1.  PSoC5 can work with TTL logic (0-5V). But the Regulator (ZLDO330) used in FTK can give output of only 3.3V. So if you are planning to use FTK directly in your project, then try to operate at 3.3V itself. Else if you are planning to use PSoC5 chip only in your board, it can be made to operate at 5V.


          2. Please refer to the Hardware Jumper settings section of the User Guide - http://www.cypress.com/?docID=22539 (Page No - 35/44)





          • 2. Re: Logic Levels?





            PSoC 3/5 has 4 quadrants which can be powered with 4 different voltages for Port I/O pins. Different quadrants can be powered with different voltages depending on the requirement.


            This feature cannot be used in FTK as all the Vddio pins have been connected with 3.3V. Using DVK CY8CKIT-001 will come handy.


            Low cost PSoC3 kit CY8CKIT-030 will be out by around WW11, and PSoC5 kit CY8CKIT-050 will be out by around WW14.







            • 3. Re: Logic Levels?

              Small Correction, Yes there are 4 quadrants in PSoC5/PSoC3, and each quadrant can be powered with different supplies. On the FTK two of the VDDIO supplies are hardwired to 3.3 Volts(VDDIO1 and VDDIO3). However the other two VDDIO supply are terminals are connected to VDD terminal(VDDIO0 and VDDIO2). This implies the voltage at VDD appears at these 2 VDDIOs. This voltage is configurable using the jumper J1. It can be set to 3.3 Volts(regulator output) or it can be set to 5Volts(VBus from USB).


              This is amazing because you can easily interface PSoC3/PSoC5 with other chips without the need for a level translator. I hope this helps!