EZ-USB Datasheet, PDF (62/334 Pages) Cypress Semiconductor – The EZ-USB USB Integrated Circuit

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