From c499a0b7550ba26e4b26e11ae13935f094f22ddc Mon Sep 17 00:00:00 2001 From: Bert van Hall Date: Tue, 22 Jul 2014 10:33:50 +0200 Subject: 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 --- LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'LUFA/Drivers/USB/Core') diff --git a/LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c b/LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c index f8b0fc6af..b5de862f1 100644 --- a/LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c +++ b/LUFA/Drivers/USB/Core/XMEGA/USBController_XMEGA.c @@ -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 -- cgit v1.2.3