Datasheet

PIC16C745/765

DS41124D-page 60 Preliminary  1999-2013 Microchip Technology Inc.

10.5 USB Register Map

The USB Control Registers, Buffer Descriptors and

Buffers are located in Bank 3.

10.5.1 CONTROL AND STATUS REGISTERS

The USB module is controlled by 7 registers, plus

those that control each endpoint and endpoint/

direction buffer.

10.5.1.1 USB Interrupt Register (UIR)

The USB Interrupt Status Register (UIR) contains flag

bits for each of the interrupt sources within the USB.

Each of these bits are qualified with their respective

interrupt enable bits (see the Interrupt Enable Register

UIE). All bits of the register are logically OR'ed

together to form a single interrupt source for the micro-

processor interrupt found in PIR1 (USBIF). Once an

interrupt bit has been set, it must be cleared by writing

a zero.

U-0 U-0 R/C-0 R/C-0 R/C-0 R/C-0 R/C-0 R/C-0

— — STALL UIDLE TOK_DNE ACTIVITY UERR USB_RST R = Readable bit

C = Clearable bit

U = Unimplemented bit,

read as ‘0’

-n = Value at POR reset

bit7 bit0

bit 7-6: Unimplemented: Read as '0'

bit 5: STALL: A STALL handshake was sent by the SIE

bit 4: UIDLE: This bit is set if the USB has detected a constant idle on the USB bus signals for 3 ms. The idle

timer is reset by activity on the USB bus. Once a IDLE condition has been detected, the user may wish

to place the USB module in SUSPEND by setting the SUSPEND bit in the UCTRL register.

bit 3: TOK_DNE: This bit is set when the current token being processed is complete. The microprocessor

should immediately read the USTAT register to determine the Endpoint number and direction used for

this token. Clearing this bit causes the USTAT register to be cleared or the USTAT holding register to be

loaded into the STAT register if another token has been processed.

bit 2: ACTIVITY: Activity on the D+/D- lines will cause the SIE to set this bit. Typically this bit is unmasked

following detection of SLEEP. Users must enable the activity interrupt in the USB Interrupt Register

(UIE: 191h) prior to entering suspend.

bit 1: UERR: This bit is set when any of the error conditions within the ERR_STAT register has occurred. The

MCU must then read the ERR_STAT register to determine the source of the error.

bit 0: USB_RST: This bit is set when the USB has decoded a valid USB Reset. This will inform the MCU to

write 00h into the address register and enable endpoint 0. USB_RST is set once a USB Reset has been

detected for 2.5 microseconds. It will not be asserted again until the USB Reset condition has been

removed, and then reasserted.

Note 1: Bits can only be modified when UCTRL.SUSPND = 0.