4 EZ-USB Input/Output
4.1
Introduction
The EZ-USB chip provides two input-output systems:
•
•
A set of programmable IO pins
A programmable I2C Controller
This chapter begins with a description of the programmable IO pins, and shows how they
are shared by a variety of 8051 and EZ-USB alternate functions such as UART, timer and
interrupt signals.
The I2C controller uses the SCL and SDA pins, and performs two functions:
•
•
General-purpose 8051 use
Boot loading from an EEPROM
Note
2.2-KB to 4.7-KB pullups are required on the SDA and SCL lines.
This chapter describes both the programming information for the 8051 I2C interface, and
the operating details of the I2C boot loader. The role of the boot loader is described in
Chapter 5, "EZ-USB Enumeration and ReNumeration ."
EZ-USB TRM v1.9
Chapter 4. EZ-USB CPU
Page 4-1
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