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6399A–DRMSD–13-Oct-08

ATSAM2553

3.4

Keyboards/Switches/Sliders/LEDs Scanning Interface

The scanning interface consists of hardwired logic. It time multiplexes keyboard, switches and

LEDs connections therefore minimizing the amount of wiring required. It communicates with the

P16 through an 304 x 11 dual port RAM and a few control registers. When a new incoming event

is detected, such as key-on, key-off or switch change, the scanning interface will notify the P16

by indicating the type of event. The P16 then simply reads the dual port RAM to get the corre-

sponding parameter, such as velocity or switch status. Conversely, the P16 simply writes into

the dual port RAM the led states to be displayed and the scanning interface will then take care of

time multiplexing the display.

The scanning interface uses an unique key velocity detect scheme with a pseudo-logarithmic

time scale. This allows velocities to be accurately detected, even when keyboard keys are

pressed very softly.

Finally a built-in 10-bit analog to digital converter (ADC) allows the connection of up to 16 contin-

uous controllers through external analog multiplexers such as the 4051.

3.5

LCD Display Interface

The LCD display interface uses a dedicated bidirectional data bus (DB0-DB7) an Instruc-

tion/data control RS, a read write signal R/W and an enable signal ENB. Built-in features are

included to accommodate even the slowest LCD displays.

3.6

Flash Programming

The ATSAM2553 enables programming Flash memories in three different ways:

• Blank Flash programming is done by the debug interface. This mode is very slow and should

be reserved for the initial boot sector programming.

• Program update. All the Flash content can be re-programmed. The ATSAM2553 cannot play

music during the Flash erase and programming. A specific firmware is used to program Flash

with the DSP

• Parameters update, e.g. in keyboard applications, backup parameter and sequencer song. If

the Flash enables concurrent read during program/erase, it is possible to backup parameters

in the upper memory plane while the µp firmware is running on the lower plane. The

ATSAM2553 cannot play music during the parameter backup because sound samples are

stored in both memory planes.

3.7

Flash Features

•3.3v or 5v

• Access time: 90 ns (for 12.288 MHz crystal)

• Dual plane with concurrent read while program/erase recommended for parameters backup.