FT221XS-R datasheet(35/45 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

Memory Area Description

Word Address

User Memory Area 2

Accessible via USB, I2C and FT1248

0x3FF - 0x80

Configuration Memory Area

Accessible via USB, I2C and FT1248

0x7E - 0x50

Configuration Memory Area

Cannot be written

0x4E - 0x40

User Memory Area 1

Accessible via USB, I2C and FT1248

0x3E - 0x12

Configuration Memory Area

Accessible via USB, I2C and FT1248

0x10 - 0x00

Figure 9.1: Simplified memory map for the FT-X

User Memory Area

The User Memory Areas are highlighted in Green on the memory map. They can be read and written via

both USB and FT1248 on the FT221X. All locations within this range are freely programmable; no areas

have special functions and there is no checksum for the user area.

Note that the application should take into account the specification for the number of write cycles in

Section 6.4 if it will be writing to the MTP memory multiple times.

Configuration Memory Area (writable)

This area stores the configuration data for the device, including the data which is returned to the host in

the configuration descriptors (e.g. the VID, PID and string descriptions) and also values which set the

hardware configuration (the signal assigned to each CBUS pin for example).

These values can have a significant effect on the behaviour of the device. Steps must be taken to ensure

that these locations are not written to un-intentionally by an application which is intended to access only

the user area.

This area is included in a checksum which covers configuration areas of the memory, and so changing

any value can also cause this checksum to fail.

Configuration Memory Area (non-writable)

This is a reserved area and the application should not write to this area of memory. Any attempt to write

these locations will fail.

9.4 Hardware Requirements

The hardware is the same as for a typical USB-FT1248 application and no additional hardware or

programming voltages are required. For the USB connections, either a bus-powered configuration (see

Section 7.1 and 7.3) or a self-powered configuration (see Section 7.2) could be used.

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