What is the difference between BCSP and H4?
If you have a BCSP device and require a H4 card (or vice versa), please contact firstname.lastname@example.org as we have H4 versions of all our Bluetooth products (with the exception of BL-521, which is in neither mode) H4 is the standard way of transmitting Bluetooth data over a UART as defined in the Bluetooth specifications. The majority of software stacks from independent vendors will communicate with our products in H4 mode without any additional modification to the stack. BCSP is a proprietary CSR protocol (more details below), thus for a software stack to communicate with our products in BCSP mode, it must have a BCSP module written for it - either by the vendor, or by the user. To support flexible partitioning of software between the host and the Bluetooth subsystem, and to enhance the speed of product design, CSR offers a multi-protocol communications link known as BlueCore Serial Protocol (BCSP). BCSP provides a more sophisticated option than currently defined Bluetooth serial protocols: H4/UART or H3/RS232. (CSR does not support H3/RS232 because of its high host memory and processing requirements.) BCSP adds error checking and retransmission to accommodate any dropped data during 'wake-up', and flow control for several logical channels, while simultaneously reducing the processing overhead. It allows developers to link at HCI, L2CAP, RFCOMM, or SDP layers, providing flexibility for companies that have already begun software development.