Copyright © 2014 Future Technology Devices International Limited

4

Document No.: FT_000648

FT121 ENHANCED USB DEVICE CONTROLLER WITH SPI SLAVE IC

Datasheet Version 1.2

Clearance No.: FTDI#

312

Table of Contents

1

Typical Applications...................................................................... 2

1.1

Part Numbers...................................................................................... 2

1.2

USB Compliant .................................................................................... 2

2

Block Diagrams ............................................................................ 3

3

Device Pin Out and Signal Description.......................................... 6

3.1

TSSOP-16 Package Pin Out ................................................................. 6

3.2

QFN-16 Package Pin Out..................................................................... 6

3.3

Pin Description ................................................................................... 7

4

Function Description..................................................................... 9

4.1

Functional Block Descriptions ............................................................. 9

4.2

Interrupt Modes................................................................................ 10

4.3

SPI Slave Interface........................................................................... 10

4.3.1

4-wire write operation ................................................................................................ 11

4.3.2

4-wire read operation................................................................................................. 11

4.3.3

3-wire write operation ................................................................................................ 12

4.3.4

3-wire read operation................................................................................................. 12

5

Endpoint Buffer Management ..................................................... 14

5.1

Endpoint Buffer Management in Default Mode .................................. 14

5.2

Endpoint Buffer Management in Enhanced Mode .............................. 15

6

Commands and Registers ........................................................... 17

6.1

Command Summary.......................................................................... 17

6.2

Initialization Commands ................................................................... 22

6.2.1

Set Address Enable .................................................................................................... 22

6.2.2

Set Endpoint Enable ................................................................................................... 22

6.2.3

Set Mode .................................................................................................................. 22

6.2.4

Set Interrupt............................................................................................................. 24

6.2.5

Set Endpoint Configuration (for Enhanced Mode) ........................................................... 24

6.3

Data Flow Commands ....................................................................... 25

6.3.1

Read Interrupt Register .............................................................................................. 25

6.3.2

Select Endpoint ......................................................................................................... 27

6.3.3

Read Last Transaction Status ...................................................................................... 27

6.3.4

Read Endpoint Status ................................................................................................. 28

6.3.5

Read Buffer............................................................................................................... 29

6.3.6

Write Buffer .............................................................................................................. 29

6.3.7

Clear Buffer .............................................................................................................. 29

6.3.8

Validate Buffer .......................................................................................................... 29

6.3.9

Set Endpoint Status ................................................................................................... 30

6.3.10

Acknowledge Setup ................................................................................................ 30