Being charged with child pornography in Pennsylvania is incredibly serious. The first step that a person needs to take in defending against allegations of this nature is to engage with an experienced Pennsylvania sex crimes attorney from as soon as possible. The attorney will be able to analyze the discovery, that is the evidence in the case. They'll be able to find if there's any weaknesses in the prosecution's case. They'll be able to determine if, for example, the police conducted an illegal search. Did they have the lawful right to, for example, search your home or your computer, cell phone, laptop, whatever the case may be?
If they did not have a lawful right to do so, for example, if they search without a search warrant, your attorney can file a motion to suppress the evidence, the evidence being whatever may have been recovered on the computer or the cell phone. For example, if evidence is suppressed, it would not be able to be used against the defendant in court. An attorney could take other steps to determine if, could the computer, the cell phone have been somebody else's? Was it shared among household members?
There's multiple steps an attorney can take on your behalf. They'll be able to help you best understand and navigate the criminal process. If you're accused of child pornography, they should be involved from as early as possible in the case.