28.5.2 Control B
| Name: | CTRLB |
| Offset: | 0x1 |
| Reset: | 0x00 |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| URESUME | GNAUTO | GNAK | ATTACH | ||||||
| Access | R/W | R/W | R/W | R/W | |||||
| Reset | 0 | 0 | 0 | 0 |
Bit 3 – URESUME Upstream Resume
This bit initiates an upstream resume on the USB bus.
The application must not initiate an upstream resume unless the USB bus has been in the suspend state for at least 5 ms. See the SUSPENDED bit in the Bus State (USB.BUSSTATE) register.
Writing a ‘0’ to this bit has no effect.
Writing a ‘1’ initiates an upstream resume on the USB
bus
This bit is cleared when an upstream resume has been initiated.
Bit 2 – GNAUTO Automatic Global NAK
This bit selects if the peripheral automatically sends an Automatic Global NAK (GNAK) on receiving a SETUP transaction.
| Value | Description |
|---|---|
| 0 | Automatic GNAK is disabled |
| 1 | Automatic GNAK is enabled |
Bit 1 – GNAK Global NAK
Writing this bit to ‘1’ causes all endpoints to respond with NAK
on any transaction. When the Global NAK has been enabled throughout
the USB peripheral, the Global NAK Done (GNDONE) flag in the Interrupt
Flags B (INTFLAGSB) register is set.
| Value | Description |
|---|---|
| 0 | Global NAK is disabled |
| 1 | Global NAK is enabled |
Bit 0 – ATTACH Attach
This bit controls whether the internal pull-up on the D+ line is enabled.
| Value | Description |
|---|---|
| 0 | The internal D+ pull-up is disabled and the device is detached from the USB bus |
| 1 | The internal D+ pull-up is enabled and the device is attached to the USB bus |