UM0212

USB OTG demonstration software

9/13

2.3

STOTG04 registers

The STOTG04 has four types of registers (see Figure 5).

●

Control registers

●

Interrupt registers (source, latch, and falling/rising edges)

●

Information registers (vendor ID and product ID)

●

STOTG04 device address (2Ch or 2Dh) registers.

Having a general knowledge of the registers may prevent certain anomalies. For example, if

the J1 jumper is shorted and the "TRANSP_EN" bit has been set by mistake, the STOTG04

communication can be reinstated by opening J1. Knowing the READ and WRITE sequence

is important for using the interrupt registers, especially when multiple registers are changing

at the same time. In these cases, the interrupt’s "falling edge" and "rising edge" registers

have the highest priority. For example, to monitor the VBUS_VLD interrupt (this is usually

done when the charge pump is switched ON):

1.

set the VBUS_VLD bit in the "rising edge" register and the VBUS_DRV bit in "Control

Register2"

2.

Click on the "Write All" button

The register WRITE order (priority) is:

–

"Write [Rising Edge (VBUS_VLD)]" THEN

–

"Write [Control Register 2 (VBUS_DRV)]".

The user should always monitor the "Status" field to see if READ or WRITE operations are

successful.

Note that the TRANSP_EN bit in the control register 1 and the 2V7_EN bit in the control

register 3 are enabled only when the STOTG04E device version is selected. The "VendorID"

and "ProductID" registers are read-only and provide the STOTG04’s identity.

Note:

See the STOTG04 USB OTG full-speed transceiver datasheet for details.

Figure 5.

USB OTG demonstration user interface registers

Note:

These are STOTG04 register settings after the first "Read All" instruction.

Control

STOTG04

information (read-only)

STOTG04

device address

Serial port

address field Control buttons

Interrupt source,

latch, and falling/rising

edges

STOTG04

device version