For linux and macos developement. You can download the SDK from the following link. You can send email to contact firstname.lastname@example.org to get more informations
LINUX/MACOS SDK Publish Page
contact email email@example.com
QHYCCD Low Level (1) USB Protocol
QHYCCD low level （1） USB protocol is a communication protocol based on the USB IO level. You do not need use any API or SDK. Just read the document and use the basic USB IO communication method to control and read data from the camera. This protocol gives the maxium flexibility for both windows, linux, embeded linux, Mac/OS, Android and it is driver/OS independence.
You can go to the QHYCCD forum -> Developer board to obtain this protocol and the camera firmware HEX/IMG file. The developer board require the developer level on QHYCCD forum. You can send message on forum or send email to firstname.lastname@example.org to request this user level.