Eliminate Overswing on GPIO Digital Output Waveform for PSoC 6 MCU – KBA226752

Author: WangS_81           Version: **


For PSoC 6 MCU devices, sometimes there would be overswing shown on the GPIO digital output waveform, as shown below. This phenomenon occurs commonly on the rising/falling edge when the output is a square waveform and reverts at a relatively high frequency.



The root-cause of this issue might be the default setting of corresponding GPIO’s “Slew rate” is as “Fast”.


To solve this issue, you can try changing the “Slew rate” as “Slow”. A slower slew rate results in reduced EMI and crosstalk; this is recommended for low-frequency signals or signals without strict timing constraints. You can select slow mode for signals less than 1-MHz switching rate and benefit from slower transition edge rates.


Once the slow slew rate is selected, the overswing disappears, as shown below:


Set GPIO Slew Rate


PSoC Creator 4.2


Double-click the target GPIO to open the customizer in TopDesign, and navigate to the “Output” tab.


Modus Toolbox 1.1


Double-click the “design.modus” application or click Configure Device item to open Device Configurator:



In Device Configurator, check the target GPIO and configure the Slew Rate item shown in the Parameters list on the right of capture: