PSoC™ 5, 3 & 1

Anonymous
Not applicable

I am having a problem configuring my ADC in the way that is required. The range of my ADC is +/-6. We need to be configured that way; when the input voltage at -6V, then my ADC hex value should be 0x0000. When the voltage is 0V, then the LCD should display the half of my ADC value in hex, and my maximum ADC value which is 0xFFFF is equal to my maximum voltage which is +6V.

Please check the attachment to observe my result. It's working, but the problem with it, the Voltage -0.001V is equal to 0xFFFF, but we need it to be the half of whatever the ADC value is, and my 0x0000 should be -6v.

I am using the same kit as in the link below, which is PSoC 5LP.
http://www.cypress.com/documentation/development-kitsboards/cy8ckit-050-psoc-5lp-development-kit

Thanks!

1 Solution
Level 8
Level 8

You cannot handle negative voltages with the PSoC, they might even destroy it. (Except when using differential input, but even then the voltages cannot be below ground).

Apart from that: 0x000 corresponds to 0V, and negative voltages are represented as "two's complement" - a '-1' is then 0xFFFF. I think the ADC component data sheet explains that.

6 Replies
Level 8
Level 8

You cannot handle negative voltages with the PSoC, they might even destroy it. (Except when using differential input, but even then the voltages cannot be below ground).

Apart from that: 0x000 corresponds to 0V, and negative voltages are represented as "two's complement" - a '-1' is then 0xFFFF. I think the ADC component data sheet explains that.

Anonymous
Not applicable

I am using delsig ADC, and I am using the differential input mode. My range is +/-6.2. So, can you explain why I can't use a negative voltage? I thought this what the differential input mode for!

Level 10
Level 10

The PSoC (all of them) specify in absolute maximum ratings the lowest and highest voltage that may be applied to any pin. This is GND to Vdd,

No negative voltages (less than GND) are allowed.

Bob

Anonymous
Not applicable

That's so confusing to me. In the attached picture, I got the shot from the Delsig datasheet, it says the Delsig can take negative voltage. I am not talking about pins, I am talking about the ADC_Delsig.

Also, it allows me to setup the range at +/- voltage as it appears on the second shot.

If the ADC_Delsig can't do negative, then what all these options in the second shot for?

Thanks!

Level 8
Level 8