Posted on March 17, 2015 at 10:15
> But I 'm using a customized hardware.
A) Crystal frequency
What is the Xtal frequency?
As the abstract of CQ-STARM2 example tells, the example expects 8 MHz crystal across OSC_IN/_OUT pins.
B) D+ pull-up resistor
This USB device engine on STM32F103 requires an external D+ pull-up resistor (1k5), which is driven by a port pin. Does your board have this resistor?
STM32F103RB USB B-type connector
PA11 --------------- D-
PA12 -----------+--- D+
|
PB12 --- 1k5 ---+
GND --------------- GND
The CQ-STARM2\USBMem example supposes to drive the external resistor over a transistor using PD9, but the direct connection like above makes the circuit simple. You may assign any extra GPIO port for this purpose, except for the JTAG ports (PA13-PA15, PB4).
The example code around PD9 should be modified, according to your choice for the drive port.
Here is modification for PB
\Keil\ARM\Boards\ST\CQ-STARM2\USBMem\usbhw_STM32F10x.c
void USB_Init (void) {
RCC->APB1ENR |= (1 <<
23
); /* enable clock for USB */
USB_IntrEna (); /* Enable USB Interrupts */
/* Control USB connecting via SW */
RCC->APB2ENR |= (1 <<
3
); /* enable clock for GPIOB */
GPIOB->CRH &= ~0x000F0000; /* clear port PB12 */
GPIOB->CRH |= 0x00040000; /* PB12 Floating input */
}
void USB_Connect (BOOL con) {
GPIOB->CRH &= ~0x000F0000; /* clear port PB12 */
if (con) {
GPIOB->BSRR = 0x1000; /* set PB12 */
GPIOB->CRH |= 0x00030000; /* PB12 General purpose output push-pull, 50 Mhz */
CNTR = CNTR_FRES; /* Force USB Reset */
CNTR = 0;
ISTR = 0; /* Clear Interrupt Status */
CNTR = CNTR_RESETM | CNTR_SUSPM | CNTR_WKUPM; /* USB Interrupt Mask */
} else {
CNTR = CNTR_FRES | CNTR_PDWN; /* Switch Off USB Device */
GPIOB->CRH |= 0x00040000; /* PB12 Floating input */
}
}
Tsuneo
