Hi,
I found this project while looking for STM32 based i2c-tiny-usb alternatives. Since I only had a couple of maplemini boards on stock at home, I tried to execute your code directly with no success. Even though the used board (with an STM32F103CBT6 µC) is comparable and similarly wired (wr. to the USB pins), I wasn't able to establish a USB connection. After comparing the schematics for "bluepill" and "maplemini" based development boards I realized, that the maplemini uses GPIOB9 to disable USB connectivity through a transistor on USBDP. The bluepill board directly uses a pull up resistor on USBDP. Configuring GPIOB9 as output and clearing it afterwards, brought me success :-)
I encapsulated my changes in an #ifdef, such that the code needs to be build with CFLAGS=-DUSE_MAPLEMINI in order to include my changes. Feel free to merge, if you are interested :-)
daniel-thompson
commented
4 years ago
Hi, I found this project while looking for STM32 based i2c-tiny-usb alternatives. Since I only had a couple of maplemini boards on stock at home, I tried to execute your code directly with no success. Even though the used board (with an STM32F103CBT6 µC) is comparable and similarly wired (wr. to the USB pins), I wasn't able to establish a USB connection. After comparing the schematics for "bluepill" and "maplemini" based development boards I realized, that the maplemini uses GPIOB9 to disable USB connectivity through a transistor on USBDP. The bluepill board directly uses a pull up resistor on USBDP. Configuring GPIOB9 as output and clearing it afterwards, brought me success :-) I encapsulated my changes in an #ifdef, such that the code needs to be build with CFLAGS=-DUSE_MAPLEMINI in order to include my changes. Feel free to merge, if you are interested :-)
BR Matthias