I'm an electrical engineering student and I've just started to learn microcontrollers.I want to know is there any way to connect my board(I uploaded its picture)to computer when I'm using USART without USB to TTL module?
closed as unclear what you're asking by Elliot Alderson, RoyC, Oleg Mazurov, Simon B, Finbarr Aug 21 at 13:50
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(a)it's a pc,the os is windows 10,(b)USB,vga,hdmi,i guess only usb is appropriate for that,(c)actually it's about the cost,i just want to know if there is any way to do that without purchasing a module it's better than buying one.
From the information in your comment, you have no other sensible choice than using a USB to TTL adapter, as you have no other suitable interface on your PC except USB.
Also, it is going to cost more in components and PCB etc. to make a USB to TTL adapter yourself, than buying one.
While it would require substantially more complex firmware on the MCU and is likely unwise for you right now for that reason, the STM32F103 has a native USB device port which your board appears to show brought to a mini-USB port.
By connecting that directly to your computer you can implement a serial-like connection over USB without a converter, either CDC/ACM or some other protocol, though getting this initially recognized on Windows may be painful. And it's practically useful to have a simple serial setup to see debug output while working on the USB code.
Before you pursue that route consider that you will also need to program your board. Unlike some later STM32's the STM32F103's ROM bootloader does not speak USB. So you would either need to use something like an external converter to speak to the bootloader via serial, or to use an SWD adapter for programming. The latter is by far the best solution. It is also possible to tunnel debug output through SWD in various ways, though non trivial to set up with the lower cost implementations.
If you needed to produce a lot of systems, there are 3rd party bootloaders that do speak USB you could flash using SWD or serial, and continue from there with USB alone - ports of Arduino to this platform often do that. But first you have the chicken and egg problem of getting working code that can speak USB on there. For that, realistically you should buy not only a USB to 3v3 serial adapter, but also an SWD adapter.