Cypress Semiconductor SL811HS Bedienungsanleitung PDF herunterladen (Seite 7)

Cypress Semiconductor Corporation

SL811HS and SL811HST: Application Notes

and specifications contained in this document are subject to change without

notice.

Date: 07/26/01

Revision: 1.21

Page: 7

2. SL811HS HOST OR SLAVE MODE

2.1. Overview

The SL811HS supports both USB Host and USB Slave modes. These modes are selectable

by a single pin that can be permanently connected to ground for Host mode, or left

unconnected for Slave mode. Optionally, the Mode Select pin can be driven by a GPIO pin of

a host CPU thus allowing software selection of the USB Host/Slave modes. In certain

applications, the user may need to support both Host and Slave modes with a single SL811HS

controller. The following will describe an application whereby the SL811HS can be utilized to

support both modes. A schematic diagram is provided (Figure 1: SL811HS circuit diagram) to

illustrate a possible implementation.

2.2. Hardware requirements

There is a minimum set of requirements to implement the host/slave functions with a single

SL811HS. These are described below in Table 1 below.

2.1.1 External Controller and USB connectors

The application requires an external microcontroller that can provide at least two 3.3V GPIO

lines to control the Host/Slave mode pin, and sufficient power to supply to the USB connector

when Host mode is enabled.

The USB 1.1 specification requires the use of different USB connectors for Host and Slave

ports, and specific termination resistors for each port. The schematic diagram (Figure 2:

SL811HS circuit diagram/Figure 2: SL811HS host/slave diagram) illustrates the requirements

for each mode.

2.3. Power On and Reset Mode

The SL811HS needs to be reset and reconfigured when switched to different modes. The

SL811HS has a hardware RESET input that can be used rather than recycling power on/off

whenever the mode switch is initiated. For instance, when switching to the Host mode, after

the hardware reset, the user sets bit 7 = ‘1’ of Control2 Register (cSOFcnt =0x0F), SL811HS

will be in host mode. Please note when both Host and Slave USB connectors are present as

shown in the diagram, only one device can be attached at any one time. The following

summary of actions has to be accomplished in switching between modes:

1 2 3 4 5 6 7 8 9 10 11 12 ... 42 43

Keine Kommentare

Cypress Semiconductor SL811HS Bedienungsanleitung Seite 7