ISP1109 データシートの表示（PDF） - Philips Electronics

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ISP1109

Universal Serial Bus transceiver with carkit support

Philips Electronics 

Philips Semiconductors

ISP1109

USB transceiver with carkit support

7. Functional description

7.1 Serial controller

The serial controller includes the following functions:

• Serial Controller interface (SPI or I2C-bus)

• Device Identification registers

• Control registers

• Interrupt registers

• Interrupt generator.

The serial controller acts as an SPI slave or I2C-bus slave.

All the registers are the same as that in SPI or I2C-bus mode. In I2C-bus mode, the

registers are accessed in 8-bit width (bits 0 to 7) for each address. In SPI mode, there are

25 bits for each address, only bits 0 to 7 are useful while bits 8 to 24 are don’t cares.

At hardware reset including power-on reset, the level on pin SPI_I2C_SEL will determine

whether the SPI or I2C-bus interface is active. If SPI_I2C_SEL = LOW, the SPI interface is

selected. If SPI_I2C_SEL = HIGH, the I2C-bus interface is selected.

7.2 VBUS detector

The VBUS detector provides voltage level detection on VBUS. If VBUS is above the VBUS

session valid comparator threshold voltage (Vth(svc)), logic 1 will be stored in

bit VBUS_DET of the Interrupt Source register. If VBUS is below Vth(svc), logic 0 will be

stored.

7.3 ID detector

In normal power mode, that is, when both VCC and VCC(I/O) are present, the ID detector

senses the condition of the ID line and can differentiate between the following three

conditions:

• ID pin is floating (bit ID_FLOAT = 1)

• ID pin is shorted to ground (bit ID_GND = 1)

• ID pin is connected to ground through resistor RDN(ID) (bits ID_FLOAT and ID_GND

are logic 0).

The recommended procedure to detect the status of ID using software is:

1. When nothing is connected, ID is in the ID_FLOAT state. Enable the ID_FLOAT

interrupt (falling edge).

2. If an interrupt occurs, read the Interrupt Latch register. If ID changes, bit ID_FLOAT is

set.

3. The software waits for sometime, for example: 100 ms, to allow mechanical

debounce.

4. The software reads the Interrupt Source register, and checks bits ID_FLOAT and

ID_GND.

9397 750 13355

Product data sheet

Rev. 01 — 14 July 2005

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

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