HS402 firmware v 1.5 - crosstalk between channels.

[otapix]

Hello In the HS402 oscilloscope with firmware version 1.5, crosstalk is created between the channels. If both channels are enabled in the app, part of the signal connected to one channel is visible on the other channel. The problem does not arise if only one channel is enabled in the application. At first I thought I had a damaged BlackPill board, but I checked it on another board and the problem also appears. I tested connecting the input signal through a divider and directly to ports PA3, PA5. The problem still persists so it is not related to a divider or GND offset. I also made the HS102 oscilloscope and there is no problem there.

Link for screenshot https://justpaste.it/9nttq

CH-1 - connected 1kHz square signal CH-2 - nothing connected or GND

[martinloren]

Crosstalk does exists but it should be in a quantity much lower that the test showed. What is the circuit used? I can control the cross-noise just on the PCB released. I'll release soon the tests including crosstalk amount.