Discovery board doesn't responsive

Apr 26, 2013 at 11:08 AM
Edited Apr 26, 2013 at 11:09 AM
Hello, All

I have updated my stm32f4discovery board to netmf 4.2 successfully and even ran a test program, which blinking led, like this:
OutputPort led = new OutputPort(Cpu.Pin.GPIO_Pin1, false); //PA1 on discovery board

while (true) {
  led.Write(true);
  Thread.Sleep(500);
  led.Write(false);
  Thread.Sleep(500);
}
But after changing output port to Cpu.Pin.GPIO_Pin12 my board become not responsive to mfdeploy and Windows doesn't recognize my board as proper usb-device.

After reading of stm32f4discovery datasheet, I learned that GPIO_Pin12 is PA12 that connected to CN5 usb on DP signal.

I think that this is a problem. My program corrupts the legal usb data signals and computer usb-host can't understand it.

Also, after upload a Tinybooter.hex to the board a ST-Link doesn't see the device on CN1 usb-port and I can't erase board firmware and starting over.

Please, help!

p.s. sorry for my english.
Apr 26, 2013 at 2:37 PM
I found the solution.

The problem is that after uploading Tinybooter.hex, this firmware changes SWD pins and ST-LINK software can't connect to ST-LINK on hardware board, because it can't understand the protocol. To solve this problem ST-LINK software must connect to board while firmware not yet initialized.

For that we need to press the Reset button on board, start "Erase chip" in menu "Target" and quickly release Reset button.

I hope this solution help anyone like me. :)