jtagprogrammerst-linkstm32f1swd
I have a question about designing st-link v2. According to the schematics provided by st.com Please help me in analyzing this schematic. Why boot0 was pulldown with a 100k resistor but connected boot1 without GND resistor.
According to the AN2586, the pin boot0 and boot1 must be connected to a VCC or GND 10k resistor.
But this point is not met
First of all, you are right, if your board has already got a supply voltage source you do not have to connect ST-Link's VDD pin.
The second thing I would recommend you is to open the STM32F411 Nucleo board's reference manual and look at the schematics. Especially the part where the ST-Link is connected to the controller on the board.
By ST Microelectronics, SWCLK, SWDIO, NRST and SWO (and GND of course) are connected to the target MCU. The additional SWO pin is used for debug purposes, you can access printed data with the printf function through this pin with ST-Link Utility.
The Printf via SWO Viewer displays the printf data sent from the target through SWO.
So I can recommend you to connect SWO as well, can be useful later. Connect your MCU to ST-Link just like they have connected the Nucleo's MCU to it.
As for boot configurations, there are three selectable options, easiest it to stick with the Main Flash and tie Boot0 to GND, but I do not know your requirements so it is up to you to choose.
Your layout is entirely lacking in decoupling capacitors. The MCU won't run with that layout and the clock probably won't even oscillate.
Best Answer
Right below Figure 10 of AN2586 it mentions:
These pins can be tied directly to VDD or GND, but it is common practice to use resistors for a few reasons.
Series resistors can provide some current-limiting protection to the microcontroller pins.
Putting at least one resistor between the pin and VDD/GND allows for easier rework if the initial design assumptions/requirements change (e.g. oh no, we want to boot from system memory now instead of main FLASH memeory!).
Adding resistors to both VDD and GND -- and not populating one of them -- allows for switching between boot configurations with only a bill of materials (BOM) change instead of rerouting a PCB in order to achieve this.