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Fix XMEGA USB prescaler calculation 

The USB prescaler calculation for the CLK.USBCTRL register is changed to
give valid results and set the prescaler correctly.

Signed-off-by: Bert van Hall <bert.vanhall@avionic-design.de>
This commit is contained in:
Bert van Hall 2014-07-22 10:33:50 +02:00
parent 526091fba4
commit c499a0b755
1 changed files with 13 additions and 3 deletions
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16
LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c
View File

@ -109,15 +109,25 @@ void USB_Disable(void)
void USB_ResetInterface(void)
{
uint8_t PrescalerNeeded;
uint8_t nbit = 0;
#if defined(USB_DEVICE_OPT_FULLSPEED)
if (USB_Options & USB_DEVICE_OPT_LOWSPEED)
CLK.USBCTRL = (((F_USB / 6000000) - 1) << CLK_USBPSDIV_gp);
PrescalerNeeded = F_USB / 6000000;
else
CLK.USBCTRL = (((F_USB / 48000000) - 1) << CLK_USBPSDIV_gp);
PrescalerNeeded = F_USB / 48000000;
#else
CLK.USBCTRL = (((F_USB / 6000000) - 1) << CLK_USBPSDIV_gp);
PrescalerNeeded = F_USB / 6000000;
#endif
while (PrescalerNeeded && nbit < 7) {
PrescalerNeeded >>= 1;
nbit++;
}
CLK.USBCTRL = (nbit - 1) << CLK_USBPSDIV_gp;
if (USB_Options & USB_OPT_PLLCLKSRC)
CLK.USBCTRL |= (CLK_USBSRC_PLL_gc | CLK_USBSEN_bm);
else