S39421 datasheet(13/28 Pages) SUMMIT

13 / 28 page

S39421

2024 9.0 8/8/00

INSTRUCTION SET

Instruction

Start

Opcode

Address

Data

Comments

Bit

x16

READ

x(A5–A0)

Read Address AN–A0

ERASE

x(A5–A0)

Clear Address AN–A0

WRITE

x(A5–A0)

D15–D0

Write Address AN–A0

EWEN

11xxxx

Write Enable

EWDS

00xxxx

Write Disable

WRAL

01xxxx

D15–D0

Write All Addresses

2024 PGM T5 .0

FIGURE 11. DATA DOWNLOADER SEQUENCE OF OPERATION

[note: all data download timing conforms to the timing shown in Figure 5]

Data Download Mode

The Data Download mode is an alternative method of

accessing the E2PROM memory. Use of this mode allows

downloading the entire contents of the memory without

entering any commands. The DD mode is enabled after a

low to high transition on the DD pin, while continuing to

assert DD (this includes powering up the device with DD

tied high). Also, as a condition to enter this mode, the

device must not be in a state of reset. Once in Data

Download mode, the device will wait until Chip Select is

driven active. At this point, the device will output a dummy

‘0’ followed by the contents of location 0000. As long as

the SK line is toggled the S39421 will continue to output

the contents of sequential address locations. In this

manner, the configuration data that is loaded into an

interface device can be accessed in a simple manner

without requiring the logic of the interface chip to generate

the complex signals needed for the microwire interface.

Data Download mode is exited upon the first high to low

transition of the Chip Select input.

Data From

Address 000

Data From

Address 001

Data From

Address 1FE

Data From

Address 1FF

VCC

Dummy 0

2024 ILL7.1

DD Mode

Disabled

DD Mode Enabled After

RESET is released and After

DD is Taken to Logic 1

RESET

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