Connect VREF to a pin in PSoC4

[Anonymous]

I was doing some searching on how to route the internal 1.024V VREF to an external pin 1[7] and found a link to an old blog that is now dead. Any pointers would be appreciated.

       

Dead link: ...cypress.com/blog/psoc-hacker-blog/connect-vref-pin-psoc4

[Anonymous]

I did accomplish this by using a SAR_ADC and selecting an 1.024 ref with external bypass. This works but you must 'Start' and ADC before it routes the VREF to the external pin. So, a working solution but sort of a long way around.

[odissey1]

here it is: http://www.cypress.com/blog/psoc-hacker-blog

[Anonymous]

Curious the link does not work in IE but works in FireFox.

[Anonymous]

Now that I read it I like my implementation better. No need for adding an op amp and all that jazz, the VREF is already on pin 1[7] anyhow.

[Vasanth]

Hi Jeff,

Your solution will work.But to make sure that using the Vref would not affect SAR ADC performance (if you are planning to use ) a buffer stage is necessary. Please follow the example code attached.

Best Regards,
VSRS

[DaCa_4090871]

Dear VSRS,

Thanks for the sample code. I have been trying to reproduce this on PSOC 4200L (CY8C4247AZI-L433). From the looks of the registers it seems I should be able to do the same as in your sample code, however the register names are different  and this device has 2 CTBM blocks (CTBM0 and CTBM1). I've tried different options and checked this document too: https://www.cypress.com/documentation/technical-reference-manuals/psoc-4200l-family-psoc-4-registers...

But, I'm unable to get the 1024mv output on the pin the I selected. Could you please help me? What am I missing here? Thanks!

[Anonymous]

Thanks for the example code. I was not planning on using the SAR ADC. My application is very trivial and just for fun. A few weeks back we found a couple of old panel meters that use nixie tube displays. They are 3.5 digit 200mv units so I thought it would be fun to turn one into a clock and it was a good excuse to get familiar with the PSoC again. Lucy for me the CY8CKit-043 came out when I started looking for a PSoC dev kit to use.

The panel meter is a Newport unit (Omega division now) and was made in the 1970's. I found a manual for a slightly newer unit and contacted them about  the 200-A2 I have and they don't have any documentation on it. The guy who replied said it was obsolete 15 years before he started with the company and he had been there 27 years! I was impressed with how quickly they responded for such a non-important request.

Anyhow, I have it outputting the time in MV now and need to add in the ability to set the time easily and add a calibration offset. The panel meter 'may' have the ability to output the reading in s BCD format from a group of I/O pins on the unit. If it does I'll try to read those in to make sure the output makes sense, i.e. that it is not 4.99 instead of 5.00 (the decimal point is manually set by a set of I/O pins).