#1001 Board STM32F103C8_MINIMAL USB Disconnect alternative

[Tercio F Gaudencio Filho]

In the board STM32F103C8_MINIMAL, the macro usb_lld_disconnect_bus, it is a NOP, as this board doesn't have a mosfet to turn on/off the pull up on the USB line D+.

There is a work around that configures the port as output and pull the pin low, this will be equivalent to turning on/off the pull up. I use this with success for some time.

I don't know how to colaborate to the project, I'm used to GitHub Pull Requests, but in SourceForge I'm a dummy.

Here is the patch:

diff --git a/os/hal/boards/STM32F103C8_MINIMAL/board.h b/os/hal/boards/STM32F103C8_MINIMAL/board.h
index 9350c1388..d2360e096 100644
--- a/os/hal/boards/STM32F103C8_MINIMAL/board.h
+++ b/os/hal/boards/STM32F103C8_MINIMAL/board.h
@@ -136,7 +136,10 @@
 /*

  * USB bus de-activation macro, required by the USB driver.
  */
-#define usb_lld_disconnect_bus(usbp)   /* always connected */
+#define usb_lld_disconnect_bus(usbp)   do { \
+                                          palSetPadMode(GPIOA, GPIOA_USBDP, PAL_MODE_OUTPUT_PUSHPULL); \
+                                          palClearPad(GPIOA, GPIOA_USBDP); \
+                                        } while(0);

 #if !defined(_FROM_ASM_)
 #ifdef __cplusplus

[Giovanni Di Sirio]

Hi,

You need to provide the code also for usb_lld_connect_bus(usbp) or it would not be very useful. Posting small patches here is fine as approach, alternatively you may post on the ChibiOS forum.

[Tercio F Gaudencio Filho]

Hi!

Here we go:

diff --git a/os/hal/boards/STM32F103C8_MINIMAL/board.h b/os/hal/boards/STM32F103C8_MINIMAL/board.h
index 9350c1388..fbdaf7e2a 100644
--- a/os/hal/boards/STM32F103C8_MINIMAL/board.h
+++ b/os/hal/boards/STM32F103C8_MINIMAL/board.h
@@ -131,12 +131,17 @@
 /*

  * USB bus activation macro, required by the USB driver.
  */
-#define usb_lld_connect_bus(usbp)      /* always connected */
+#define usb_lld_connect_bus(usbp)       do { \
+                                            palSetPadMode(GPIOA, GPIOA_USBDP, PAL_MODE_INPUT); \
+                                        } while(0);

 /*

  * USB bus de-activation macro, required by the USB driver.
  */
-#define usb_lld_disconnect_bus(usbp)   /* always connected */
+#define usb_lld_disconnect_bus(usbp)    do { \
+                                            palClearPad(GPIOA, GPIOA_USBDP); \
+                                            palSetPadMode(GPIOA, GPIOA_USBDP, PAL_MODE_OUTPUT_OPENDRAIN); \
+                                        } while(0);

 #if !defined(_FROM_ASM_)
 #ifdef __cplusplus

[Tercio F Gaudencio Filho]

In my case I added a chThdSleepMilliseconds(2000); after disconnect, but I don't know if this is necessary in this #define.

[Tercio F Gaudencio Filho]

Like this:

    usbDisconnectBus(usbcdc_cfg.usbp);
    // A delay is inserted in order to computer sense the change
    chThdSleepMilliseconds(2000);
    usbStart(usbcdc_cfg.usbp, &usb_cfg);
    usbConnectBus(usbcdc_cfg.usbp);