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correctly set turn around according to cpu clock

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help to run with low speed mcu
This commit is contained in:
hathach 2020-07-01 18:44:52 +07:00
parent 77315ba7ce
commit e3974d6869
1 changed files with 26 additions and 1 deletions

27
src/portable/st/synopsys/dcd_synopsys.c

@ -255,8 +255,33 @@ static void set_turnaround(USB_OTG_GlobalTypeDef * usb_otg, tusb_speed_t speed)
}
else
{
// Turnaround timeout depends on the MCU clock
extern uint32_t SystemCoreClock;
uint32_t turnaround;
if ( SystemCoreClock >= 32000000U )
turnaround = 0x6U;
else if ( SystemCoreClock >= 27500000U )
turnaround = 0x7U;
else if ( SystemCoreClock >= 24000000U )
turnaround = 0x8U;
else if ( SystemCoreClock >= 21800000U )
turnaround = 0x9U;
else if ( SystemCoreClock >= 20000000U )
turnaround = 0xAU;
else if ( SystemCoreClock >= 18500000U )
turnaround = 0xBU;
else if ( SystemCoreClock >= 17200000U )
turnaround = 0xCU;
else if ( SystemCoreClock >= 16000000U )
turnaround = 0xDU;
else if ( SystemCoreClock >= 15000000U )
turnaround = 0xEU;
else
turnaround = 0xFU;
// Fullspeed depends on MCU clocks, but we will use 0x06 for 32+ Mhz
usb_otg->GUSBCFG |= (0x06 << USB_OTG_GUSBCFG_TRDT_Pos);
usb_otg->GUSBCFG |= (turnaround << USB_OTG_GUSBCFG_TRDT_Pos);
}
}