PSoC 5 and Analog Mux in differential mode issues | Cypress Semiconductor
PSoC 5 and Analog Mux in differential mode issues
I have currently migrated my project from a PSoC 3 to 5 (CY8CKIT-014). My analog design uses an Analog Mux Sequencer in differential mode with 6 dual inputs from GPIO. The Mux is connected directly to a differential DelSig ADC, 16-bit @ 1000 sps in multi-sample mode. Conversion results are stored in an array, and in the ADC's interrupt there is a logic to stop conversion, change mux channel and start conversion again.
In the PSoC 3 this design was working perfeclty. But when I switched to the PSoC 5 I started to get weird results from the ADC. Some input channels are converted by ADC, but output values have significant offset, and seem to be attenuaded. Other channels (mainly evenly numbered) return always the same value, regardless of voltage applied to GPIO. Furthermore this output value seems to change with PSoC reset.
I tried to use both Analog Mux and Analog Sequencer Mux, with no luck. When I connect pins directly to the ADC, conversion works properly. Using the Analog Mux in Single mode also works. So, at the moment, I ended up with two seperate muxes to drive both inputs of the ADC. It works, but my analog routing now looks like a spaghetti.
I am using PSoC Creator 1.0 Production (7727).
I can post more details if necessary.
Does anybody else had similar issues with those muxes? Or mabye there is somebody who has working project with muxes in differential mode? I would be grateful for any iformation.