FT221XS-R datasheet(30/45 Pages) FTDI

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FT221X USB 8-BIT SPI/FT1248 IC Datasheet

Version 1.3

Document No.: FT_000630 Clearance No.: FTDI# 263

8 Application Examples

The following sections illustrate possible applications of the FT221X. The illustrations have omitted pin

numbers for ease of understanding since the pins differ between the FT221XS and FT221XQ package

options.

8.1 USB to FT1248 Converter

Figure 8.1 Application Example showing USB to FT1248 host

NOTE: ALL IO LINES SHOULD HAVE A 10k PULL UP TO VCCIO

The FT1248 can be used with 1-bit, 2-bit, 4-bit or 8-bit wide data. The Figure 8.1 is showing 8 bit mode.

By using 8 data bits you need fewer clock cycles to get the data across.

The FT221X is the slave device and the external FPGA/MCU is the bus master. The FT221X will auto

detect the bus width from the initial command byte sent by the controller. If not using all 8 data lines the

pins may be left unterminated as an internal pull-up ensures the device detects a logic 1.

Timing diagrams for 8-bit accesses can be seen in figures 8.2 and 8.3. For further information on the

mode see AN_167 FT1248 Basics from the FTDI website.

FT221XS-R Datasheet(PDF) 30 Page - Future Technology Devices International Ltd.