LM9830 datasheet(36/45 Pages) NSC

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An EPP read is shown in Figure 55. The handshaking for the

address cycle of a read is identical to the address cycle for a

write. The data cycle is as follows:

• The host takes STROBE high, indicating that the next operation

is a read.

• The host tristates D0-D7

• The host takes AUTOFEED low to request the first nibble from

the LM9830.

• The LM9830 places the first nibble on the ERROR, SELECT,

PE, and ACK pins.

• The LM9830 takes BUSY high to indicate the nibble is valid.

• The host latches the nibble on or after the rising edge of BUSY.

•The host takes AUTOFEED high to request the second nibble

from the LM9830.

• The LM9830 places the second nibble on the ERROR,

SELECT, PE, and ACK pins.

• The LM9830 takes BUSY low to indicate the nibble is valid.

• The host latches the nibble on or after the falling edge of BUSY.

Additional nibble reads will read from the last latched address

(useful for reading pixel data or the DataPort).

7.0 The Microprocessor Compatible Interface

In this interface the part is written to like a standard µP peripheral,

with RD (AUTOFEED), WR (STROBE), CS (INIT), ALE (SELEC-

TIN), and an 8 bit databus (D0-D7). This interface would be used

in a system where another interface (perhaps SCSI or FireWire)

was desired. Using the LM9830 in this application in a DMA

mode is relatively easy and efficient, because large blocks of

image data can easily be read through a series of RDs.

To enter the µP interface mode, the CMODE pin should be tied to

VD.

7.1 Writing to the Configuration Register (µP Mode)

The Configuration Register address is latched on the falling edge

of ALE. Data is written to that address on the rising edge of WR.

7.2 Reading From The Configuration Register (µP Mode)

The address is latched as in the previous example. For all modes

except DataPort operations, the LM9830 transmits the data at

that address on the following read. Additional nibble reads will

read from the last latched address (useful for reading pixel data).

7.3 Writing Data to the DataPort (µP Mode)

The DataPort is used to write the gamma table and the off-

set/gain coefficients to the LM9830 in a continuous stream. First,

write to register 3 to set what the data is (gamma or offset/gain)

and what color (red, green, or blue) the data is for. Then write to

registers 4 and 5 to set the initial address (usually 0), and the

R/W mode (W in this example). To write data to the DataPort,

send the Data address (6) to the DataPort followed by a serial

stream of data as shown in Figure 58. The DataPort Address

stored in registers 4 and 5 will be automatically incremented after

every write (if writing gamma data) or every second write (if writ-

ing offset/gain coefficient words).

7.4 Reading Data from the DataPort (µP Mode)

The gamma table and offset/gain coefficients can also be read

STROBE

AUTOFEED

BUSY

Addr

D0 - D7

Figure 55: Reading from the Configuration Register

(Nibble Mode)

SELECT IN

ERROR (D0, D4)

SELECT (D1, D5)

PE (D2, D6)

ACK (D3, D7)

D7-D4

D3-D0

CS (INIT)

RD (AUTO-

FEED)

Addr

D0 - D7

8-Bit Data

(STROBE)

ALE

(SELECTIN)

Figure 56: Writing to the Configuration Register (µP)

CS (INIT)

RD (AUTO-

FEED)

Addr

D0 - D7

8-Bit Data

(STROBE)

ALE

(SELECTIN)

Figure 57: Reading from the Configuration Register

(µP mode, except DataPort)

Figure 58: Writing to the Configuration Register (µP)

Datan

CS (INIT)

D0 - D7

(STROBE)

ALE

(SELECTIN)

(AUTOFEED)

Datan+1

Datan+2

LM9830 Datasheet(PDF) 36 Page - National Semiconductor (TI)

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