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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: 20

4. SL811HS HOST SOFTWARE

These sample IO subroutines are based on the SL811HS DVK. The Address location is

mapped for the ISA bus space.

The User should redefine the SL11_ADDR variable to match user’s mapping.

The next section shows how a Microcontroller can communicate with SL811HS. In successive

sections, examples will be shown for two possible operations to be performed with the

SL811HS:

- Transmit Data Transmit Data

- Receive Data Receive Data

4.1. SOFTWARE APPLICATION

The SL811HS is intended for embedded systems. This document describes general interface

routines that are required by the SL811HS host USB interface. For integration with a specific

external Microcontroller, you will need to understand the following sections to know how to

communicate with the SL811HS. The interface to the SL811HS is described using an ISA bus,

but these functions can be translated for use with any external CPU or other type of interface

bus.

4.1.1 Single Write Operation

Writing a byte to the SL811HS involves two write cycles. On the first write, the application

must write a register address into the SL811HS's Address Pointer Register. On the second

write, the actual data is written to the chip.

In an I/O mapped application, the function to write a byte to an SL811HS register is shown

below:

Program Sample 1: Single Write Function

void SL11Write(BYTE a, BYTE d)void SL11Write(BYTE a, BYTE d)

{ {

outportb(SL11_ADDR,a); outportb(SL11_ADDR,a);

outportb(SL11_ADDR+1,d); outportb(SL11_ADDR+1,d);

}}

The function to write a block of data of a specific length into the SL811HS from the buffer,

which is defined by the pointer “addr”.

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