Posted on March 19, 2014 at 19:52
> I am using the project DRD example from the STM32_USB-Host-Device_Lib_V2.1.0 examples.
The DRD (Dual Role Device) example apply both of USE_HOST_MODE and USE_DEVICE_MODE, but not USE_OTG_MODE.
\DRD\inc\usb_conf.h
#define USE_HOST_MODE
#define USE_DEVICE_MODE
//#define USE_OTG_MODE
> I am struggling to find an example of how to switch between the Host/device mode when a‘A’ USB cable (flash stick )
Under USE_HOST_MODE and/or USE_DEVICE_MODE, the ID pin interrupt is available to detect 'A' plug cable in/out. When the status of the ID pin alters, CIDSCHG bit in OTG_FS_GINTSTS register rises. Firmware reads CIDSTS bit in OTG_FS_GOTGCTL, to see the level of ID pin (0 = plug in of 'A' plug)
> and a‘B’USB cable (connected to PC for VCP serial port ).
When VBUS pin voltage rises at PC plug in, SRQINT bit in OTG_FS_GINTSTS is asserted on both of host/device mode, while VBUSASEN/VBUSBSEN bits of OTG_FS_GCCFG are enabled.
SEDET bit in OTG_FS_GOTGINT notifies VBUS voltage drop in device mode.
As of the modification of the DRD example,
1) ID pin configuration
ID pin (PA10) should be configured as input pull-up, explicitly, in USB_OTG_BSP_Init().
usb_bsp.c
void USB_OTG_BSP_Init(USB_OTG_CORE_HANDLE *pdev)
{
// EXTI_InitTypeDef EXTI_InitStructure;
#ifdef USE_STM3210C_EVAL
GPIO_InitTypeDef GPIO_InitStructure;
USB_OTG_GCCFG_TypeDef gccfg;
// set up ID pin (PA10) as input pull-up
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// enable VBUS sense
gccfg.d32 = USB_OTG_READ_REG32(&pdev->regs.GREGS->GCCFG);
gccfg.b.vbussensingA = 1 ;
gccfg.b.vbussensingB = 1 ;
USB_OTG_WRITE_REG32 (&pdev->regs.GREGS->GCCFG, gccfg.d32);
RCC_OTGFSCLKConfig(RCC_OTGFSCLKSource_PLLVCO_Div3);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_OTG_FS, ENABLE) ;
...
...
2) USB peripheral initialization
USB_OTG_BSP_Init() is called in Demo_Init(), to set up the USB peripheral in early stage.
dual_func_demo.c
void Demo_Init (void)
{
USB_OTG_BSP_Init(&USB_OTG_Core);
...
...
3) Enable cable interrupts
On ''case DEMO_IDLE'' in Demo_Application(), the above interrupts are enabled.
dual_func_demo.c
static void Demo_Application (void)
{
static uint8_t prev_select = 0;
uint16_t bytesWritten, bytesToWrite;
FRESULT res;
switch (demo.state)
{
case DEMO_IDLE:
USB_OTG_EnableCableInt(&USB_OTG_Core);
...
...
static void USB_OTG_EnableCableInt(USB_OTG_CORE_HANDLE *pdev)
{
USB_OTG_GINTMSK_TypeDef int_mask;
int_mask.d32 = 0;
/* Clear any pending interrupts */
USB_OTG_WRITE_REG32( &pdev->regs.GREGS->GINTSTS, 0xBFFFFFFF);
/* Enable the interrupts in the INTMSK */
int_mask.b.conidstschng = 1; // Connector ID status change
int_mask.b.sessreqintr = 1; // VBUS is in the valid range
USB_OTG_WRITE_REG32( &pdev->regs.GREGS->GINTMSK, int_mask.d32);
/* Enable Interrupts */
USB_OTG_BSP_EnableInterrupt(pdev);
}
4) ISR for cable interrupts
In OTG_FS_IRQHandler(), above interrupts are handled
stm32fxxx_it.c
#include ''dual_func_demo.h''
extern DEMO_StateMachine demo;
#ifdef USE_USB_OTG_FS
void OTG_FS_IRQHandler(void)
#else
void OTG_HS_IRQHandler(void)
#endif
{
if ( demo.state == DEMO_WAIT ) {
Cable_ISR_Handler(&USB_OTG_Core);
} else {
if (USB_OTG_IsHostMode(&USB_OTG_Core)) /* ensure that we are in device mode */
{
USBH_OTG_ISR_Handler(&USB_OTG_Core);
}
else
{
USBD_OTG_ISR_Handler(&USB_OTG_Core);
}
}
}
void Cable_ISR_Handler (USB_OTG_CORE_HANDLE *pdev)
{
USB_OTG_GINTSTS_TypeDef gintsts;
gintsts.d32 = USB_OTG_ReadCoreItr(pdev);
if (gintsts.b.conidstschng) // Connector ID status change
{
USB_OTG_GOTGCTL_TypeDef gotgctl;
gotgctl.d32 = USB_OTG_READ_REG32(&pdev->regs.GREGS->GOTGCTL);
if (gotgctl.b.conidsts == 0) // ID pin is low
{
demo.state = DEMO_HOST;
}
}
if (gintsts.b.sessreqintr) // VBUS is in the valid range
{
demo.state = DEMO_DEVICE;
}
/* Set flag and clear interrupt */
USB_OTG_WRITE_REG32 (&pdev->regs.GREGS->GINTSTS, gintsts.d32);
}
Tsuneo
