40.8.1 Control B
| Name: | CTRLB |
| Offset: | 0x08 |
| Reset: | 0x0001 |
| Property: | PAC Write-Protection |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| LPMHDSK[1:0] | GNAK | ||||||||
| Access | R/W | R/W | R/W | ||||||
| Reset | 0 | 0 | 0 | ||||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| NREPLY | SPDCONF[1:0] | UPRSM | DETACH | ||||||
| Access | R | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 0 | 0 | 0 | 1 | ||||
Bits 11:10 – LPMHDSK[1:0] Link Power Management Handshake
These bits select the Link Power Management Handshake configuration.
| Value | Name | Description |
|---|---|---|
| 0x0 | NO | No handshake. LPM is not supported. |
| 0x1 | ACK | ACK |
| 0x2 | NYET | NYET |
| 0x3 | - | Reserved |
Bit 9 – GNAK Global NAK
This bit configures the operating mode of the NAK.
This bit is not synchronized.
| Value | Description |
|---|---|
| 0 | The handshake packet reports the status of the USB transaction |
| 1 | A NAK handshake is answered for each USB transaction regardless of the current endpoint memory bank status |
Bit 4 – NREPLY No reply excepted SETUP Token
This bit is cleared by hardware when receiving a SETUP packet.
This bit has no effect for any other endpoint but endpoint 0.
| Value | Description |
|---|---|
| 0 | Disable the “NO_REPLY” feature: Any transaction to endpoint 0 will be handled according to the USB2.0 standard. |
| 1 | Enable the “NO_REPLY” feature: Any transaction to endpoint 0 will be ignored except SETUP. |
Bits 3:2 – SPDCONF[1:0] Speed Configuration
These bits select the speed configuration.
| Value | Name | Description |
|---|---|---|
| 0x0 | FS | Full-speed |
| 0x1 | LS | Low-speed |
| 0x2 | - | Reserved |
| 0x3 | - | Reserved |
Bit 1 – UPRSM Upstream Resume
This bit is cleared when the USB receives a USB reset or once the upstream resume has been sent.
| Value | Description |
|---|---|
| 0 | Writing a zero to this bit has no effect. |
| 1 | Writing a one to this bit will generate an upstream resume to the host for a remote wakeup. |
Bit 0 – DETACH Detach
| Value | Description |
|---|---|
| 0 | The device is attached to the USB bus so that communications may occur. |
| 1 | It is the default value at reset. The internal device pull-ups are disabled, removing the device from the USB bus. |