Nxp Semiconductors UM10237 ユーザーズマニュアル

UM10237_2

© NXP B.V. 2008. All rights reserved.

/* Wait for TDI to be set */

while (!(OTG_I2C_STS & TDI));

/* Clear TDI */

OTG_I2C_STS = TDI;

/* Add D+ pull-up through ISP1301 */

OTG_I2C_TX = 0x15A; // Send ISP1301 address, R/W=0

OTG_I2C_TX = 0x006; // Send OTG Control (Set) register address

OTG_I2C_TX = 0x201; // Set DP_PULLUP bit, send STOP condition

/* Wait for TDI to be set */

while (!(OTG_I2C_STS & TDI));

/* Clear TDI */

OTG_I2C_STS = TDI;

In this case, the role of the OTG controller is host (A-device), and the A-device switches 
roles from host to peripheral.

The On-The-Go Supplement defines the behavior of a dual-role A-device during HNP 
using a state machine diagram.   The OTG software stack is responsible for implementing 
all of the states in the Dual-Role A-Device State Diagram.

The OTG controller hardware provides support for the state transitions between a_host, 
a_suspend, a_wait_vfall, and a_peripheral in the Dual-Role A-Device state diagram. 
Setting A_HNP_TRACK in the OTGStCtrl register enables hardware support for switching 
the A-device from the host state to the device state. The hardware actions after setting 
this bit are shown in 

.