Cypress EZ-USB FX3 User Manual

EZ-USB FX3 Technical Reference Manual, Document Number: 001-76074 Rev. *F 94
Universal Serial Bus (USB)
6.9.3 USB 3.0 Fallback to USB 2.0
When the USB 3.0 termination detection or link training fails, the FX3 UIB can fall back to USB 2.0 mode. The following
function implements this fallback mechanism.
static void
CyU3PUsbFallBackToUsb2 (
void)
{
CyFx3UsbWritePhyReg (0x1005, 0x0000);
/* Force the link state machine into SS.Disabled. */
USB3LNK->lnk_ltssm_state = (CY_U3P_UIB_LNK_STATE_SSDISABLED <<
CY_U3P_UIB_LTSSM_OVERRIDE_VALUE_POS) |
CY_U3P_UIB_LTSSM_OVERRIDE_EN;
/* Keep track of the number of times the 3.0 link training has failed. */
glUibDeviceInfo.tDisabledCount++;
/* Change EPM config to full speed */
CyU3PBusyWait (2);
CyU3PSetUsbCoreClock (2, 2);
CyU3PBusyWait (2);
/* Switch the EPM to USB 2.0 mode, turn off USB 3.0 PHY and remove Rx Termination. */
UIB->otg_ctrl &= ~CY_U3P_UIB_SSDEV_ENABLE;
CyU3PBusyWait (2);
UIB->otg_ctrl &= ~CY_U3P_UIB_SSEPM_ENABLE;
UIB->intr_mask &= ~(CY_U3P_UIB_DEV_CTL_INT | CY_U3P_UIB_DEV_EP_INT | CY_U3P_UIB_LNK_INT
|
CY_U3P_UIB_PROT_INT | CY_U3P_UIB_PROT_EP_INT | CY_U3P_UIB_EPM_URUN);
USB3LNK->lnk_phy_conf &= 0x1FFFFFFF;
USB3LNK->lnk_phy_mpll_status = glUsbMpllDefault;
/* Power cycle the PHY blocks. */
GCTLAON->control &= ~CY_U3P_GCTL_USB_POWER_EN;
CyU3PBusyWait (5);
GCTLAON->control |= CY_U3P_GCTL_USB_POWER_EN;
CyU3PBusyWait (10);
/* Clear USB 2.0 interrupts. */
UIB->dev_ctl_intr = 0xFFFFFFFF;
UIB->dev_ep_intr = 0xFFFFFFFF;
UIB->otg_intr = 0xFFFFFFFF;
/* Reset the EP-0 DMA channels. */
CyU3PDmaChannelReset (&glUibChHandle);
CyU3PDmaChannelReset (&glUibChHandleOut);
/* Clear and disable USB 3.0 interrupts. */
USB3LNK->lnk_intr_mask = 0x00000000;
USB3LNK->lnk_intr = 0xFFFFFFFF;
USB3PROT->prot_intr_mask = 0x00000000;
USB3PROT->prot_intr = 0xFFFFFFFF;
UIB->intr_mask |= (CY_U3P_UIB_DEV_CTL_INT | CY_U3P_UIB_DEV_EP_INT |

Cypress EZ-USB FX3 Specifications

General

Brand	Cypress
Model	EZ-USB FX3
Category	Controller
Language	English