Overview of bluetooth issues wireless speaker tws

8. Q: When IAR debugs CC2540, is the program imported into the flash of the chip?
Answer: Indeed. CC2540 is a SOC (System On Chip) chip, its core is 8051, it needs to fetch instructions from ROM and data from RAM to run. During simulation, CC Debugger will import the program into the chip Flash, and then execute the simulation. www.bjbjaudio.com

9. Q: When the warning "Missing breakpoint, cannot run to main" appears in IAR debugging?
A: The reason for this error is that IAR for 8051 can only set up to 3 breakpoints. If you set too many breakpoints, some debugging warnings will appear after the program is downloaded. The solution is very simple, remove some breakpoints and reload the program. www.bjbjaudio.com

10. Q: Why are there many variables that cannot be viewed during IAR debugging?
A: The main reason is that the IAR compiler has set the optimization function, the automatic variables in the function and some static functions have been optimized, so the corresponding debugging information is not generated, and breakpoints cannot be viewed and set. The solution is to turn off the compiler's optimization function, right-click the tool
The Level in the program's Options -> C/C++ Compiler -> Optimizations is set to None. www.bjbjaudio.com

11. Q: The Bluetooth protocol has many layers and is complicated. How to master it?
Answer: The Bluetooth protocol is divided into 8 layers from the application layer to the physical layer, which looks complicated and has many API functions. First of all, it is not necessary to know the specific implementation of each layer. Mastering the GAP/GATT (or GAP Role and GATT Profiles) layers that are closely related to the application can satisfy most of the requirements.
Design needs; each layer of software is called through OSAL, so it is necessary to understand the basic principles of OSAL: tasks/events/messages/timers/dynamic allocation of memory; Finally, understanding the Bluetooth communication process will help development. www.bjbjaudio.com

12. Q: Is OSAL an operating system?
Answer: OSAL (Operating System Abstraction Layer) operating system abstraction layer, it is not a real operating system (it does not have Context Switch context switching function), but it cleverly organizes tasks, supports task priority, and events can be passed between tasks Communicate with messages, provide soft timers and dynamic memory allocation for tasks. The pitfall to be avoided is that the running time of a single function of an application task cannot be too long (such as flash writing that operates a large batch of data), otherwise it cannot schedule high-priority LL (Link Layer) tasks in time, resulting in interruption of Bluetooth communication. www.bjbjaudio.com 

13. Q: How do Bluetooth nodes form a piconet?
Answer: In the Bluetooth node network, there can only be one master node (Central) and multiple slave nodes (Peripheral). The slave node is the sender of the signal, and the master node is the one that scans and initiates connections. www.bjbjaudio.com

14. Q: What is the process of communication between the master node and the slave node?
Answer: When the slave node sends an advertisement signal (including additional information such as device address and device name); after the master node receives the advertisement signal, it sends a scan request to the slave node; when the slave node responds to the scan, the device discovery is completed Process. Then the master node sends a connection request to the slave node (including the connection time slot, the number of standby times of the slave node, and the connection timeout value), and the slave node responds to the connection, and the connection is established. For security reasons, access to some data requires authentication, which is done as follows: one party (which can be the master node or the slave node)
point) to ask the other party for a 6-digit password, after which the two nodes exchange security keys with each other for encryption and authentication, a process called pairing. The authentication process is cumbersome. The BLE protocol supports two nodes to save the authentication security key (usually in non-volatile memory), so that the two nodes can be quickly authenticated after the next connection. This is the binding technology. www.bjbjaudio.com