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PSoC 5, 3 & 1 MCU

keglc_4064056
New Contributor

I have a simple program to write some data using a UART and a DAC with a PSOC5. They both work but I see the digital data on the analog pin. I am using P0.0 for the DAC abd P0.1 for UART data. I see the noise on my Salea Logic analyzer and my Techtronics scope.

Any idea what may be wrong?

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odissey1
Honored Contributor II

keithglasnapp,

There surely will be a crosstalk when using adjacent pins. There is at least 10pf cross-capacitance and few hundred ohms resistance of the trace. In PSoC, analog and digital blocks are physically separated on different halved of the chip with separate grounds.  To avoid the crosswalk use analog ports 0 and 3 for analog i/o, and other ports like 1, 2, 12 (KIT-059) for digital i/o. If such separation not possible, at least separate two active pins by one grounded pin in between.

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ScottA_91
Employee

In general, when I've seen such behavior it is because something in the system isn't grounded correctly (logic analyzer, scope) or there's another power problem with your board.

That said it is very difficult to see the scale here.  Are we talking volts of difference or fractions of a millivolt?  If it is volts, that means there's definitely a problem, where are fractions of a millivolt would be reasonable and shouldn't be a cause for concern.

odissey1
Honored Contributor II

keithglasnapp,

There surely will be a crosstalk when using adjacent pins. There is at least 10pf cross-capacitance and few hundred ohms resistance of the trace. In PSoC, analog and digital blocks are physically separated on different halved of the chip with separate grounds.  To avoid the crosswalk use analog ports 0 and 3 for analog i/o, and other ports like 1, 2, 12 (KIT-059) for digital i/o. If such separation not possible, at least separate two active pins by one grounded pin in between.

View solution in original post

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