in the datasheet of the SATA R410M ,it is"The certificates in the PEM format are not supported; they will not be automatically converted to the DER format." while on the sample later it is use PEM format. does anyone use which formate successful? thank you.
I looked at the AT command. As I understand you are supposed to send it in binary. And DER is the PEM in binary without the BEGIN CERTIFICATE/END CERTIFICATE.
So maybe they just aren't super clear about it.