FTDI LibFT4222 - Overview

Application Note
AN_329 User Guide For LibFT4222
Version 1.5
Document Reference No.: FT_001060 Clearance No.: FTDI#406
5
Product Page
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1.1 Overview
The FT4222H supports 4 operation modes to allow various I
2
C/SPI devices to be connected to USB
bus. The attachable device configuration for each mode is listed below:
 Mode 0 (2 USB interfaces):
 1 SPI master, SPI slave, I
2
C master, or I
2
C slave device
 1 GPIO device
 Mode 1 (4 USB interfaces):
 SPI master connects up to 3 SPI slave devices
 1 GPIO device
 Mode 2 (4 USB interfaces):
 SPI master connects up to 4 SPI slave devices
 Mode 3 (1 USB interface):
 1 SPI master, SPI slave, I
2
C master, or I
2
C slave device
In mode 0 and 3, the connected device can be a SPI/I
2
C master or slave, depending on how an
application developer initializes the FT4222H chip. Mode 1 and mode 2 are designed to connect to
multiple SPI slave devices.
The FT4222H can be configured with up to 4 GPIO pins for user applications in mode 0 and mode 1,
but each pin is multiplexed with interrupt/suspend out/SPI slave select/I
2
C functions as listed
below:
 gpio0 / ss1o / scl
 gpio1 / ss2o / sda
 gpio2 / ss3o / suspend out
 gpio3 / wakeup/intr
If the FT4222H is initialized as an I
2
C device, with pins as shown above, the pins of gpio0 and
gpio1 will be switched to scl and sda, and cannot be used as GPIO.
By default the pin for gpio2 is configured as suspend out, and the pin for gpio3 is configured as
wakeup/intr. Only those configured GPIO pins can support GPIO read/set operation through the
corresponding endpoint.
The following diagrams show the examples of FT4222H SPI/I
2
C master connections.