Virtual USB one-to-many communication

顾念深笙

Virtual USB one-to-many communication [Copy link]

It's a bit metaphysical. Using two STM8S103F3P6 development boards and two CC1101s to send data to the virtual USB serial port on the PC, you can see two data appearing alternately in the serial debugging assistant. But when using the homemade STM8S103F3P6 PCB board (the board is fine and the program can run), only the data of one board appears. Test situation 1. Two boards AB are powered on at the same time and only A's data is displayed. Repeated many times, only A but not B. Swapping the two CC1101s still shows A's data, eliminating the relationship with CC1101. 2. One is powered on first and the other is powered on later. As a result, only the data of the latter board is displayed. Help, help

chunyang

First of all, from the description of the original poster, there is no such thing as "virtual USB". A technician must be rigorous, otherwise he cannot be called a technician. As for the original poster's question, please note that the serial port's transmitter is not allowed to be simply and directly connected in parallel. The result of direct parallel connection will cause level competition when sending data, especially when the TX output is a push-pull structure. The solution is to add a dual-input AND gate, and connect the two TX channels through the AND gate. You can also use diodes to make a line AND and then connect them in parallel.