Read a recent post on VCO using PSoC3 and thought it might be fun to directly port the traditional Astable MV circuit into a PSoC architecture.

A traditional Astable multivibrator using OpAmp would have looked like this

This is a dual supply circuit. The Opamp used as a comparator has its output charging a capacitor through a resistor, the RC constant of the setup responsible for the frequency. The resistive divider is used to switch threshold on either side of the ground thus providing a different threshold voltage for each of the output state of the circuit.

The same functionality can be mimicked in the PSoC by having a polarity controlled IDAC and capacitor to act as the RC circuit. Now the switching threshold can be easily achieved by using the hardware anaog mux in the GPIOs.

The advantage here is that the IDAC value directly determines the frequency of the output. The circuit can be modified to have a switching IDAC data bus in the two phases thus providing duty cycle control too.

In the PSoC Family dasheet (Doc number 001-44094 Rev. *F), the layout guidelines are given on page 9.  In the accompanying figure (Fig. 2-5) it is not clear what is the electrical connection of C13 and C14. Moreover, pin 46 (which is a GPIO pin - P3[2]) seems to have a via on it which connects it to ground. Can someone please clarify what needs to be done?

Thanks,

Abhijit

Dear all,

I have a quite interesting bug (?) in my projects..

It seems like the sprintf function is changing the first declared uint16 in its value, even it isn't used in the function at all!
Also when using the debugger, some variables couldn't be changed, during the next instruction the value is changed.

Does anyone of you know this behavior or even has a solution for it?
Thanks a lot in advance,
best regards,
Thomas

Hello,

I have a problem. When trying to use a script to program a PSOC3 device with MiniProg3 (WinXP) the programming doesn't work. This script comes directly from the cypress website with a few changes.

What is really wrong: If i execute the script, the programming doesn't work on a new device. When programming a device that was previously programmed with PSOC programmer 3.13.3, the script works for some reason... To find out what is wrong, i programmed a new device with the script and then started PSOC3 programmer 3.13.3. I used verify and it verified all 64 flash blocks. Only the "User NVL Array's" are unverified.

Can someone take a look at the script and tell me what is wrong?

Thx!

Hello,

I'm implementing a design with PSoC3 and I need overvoltage protecion in some of the input stages. More specifically a protection of 100Vdc. Does somebody know whether PSoC3 has any isolation or protection in its input/output pins?

Thank's. Regards.