EAeDIP128-6

Page 10

ELECTRONIC ASSEMBLY reserves

the right to change specifications

without prior notice. Printing and

typographical

errors

reserved.

>

<DC1>

len

data...

bcc

<

<ACK>

>

<DC2>

1

S

bcc

<

<ACK>

<

<DC1>

len

data...

bcc

{

// Send DC1

SendByte(len);

// Send data length

bcc = bcc + len;

// Send buf

{ SendByte(buf[i]);

bcc = bcc + buf[i];

}

SendByte(bcc);

// Send checksum

}

C-example to send a datapcket

Clear display and draw a line from 0,0 to 127,63

<DC1>

len

ESC D L

ESC G D 0 0 127 63

bcc

>

$11

$0A

$1B $44 $4C $1B $47 $44 $00 $00 $7F $3F

$2A

$06

Example fo a complete datapackage

DATATRANSFER PROTOCOL(SMALL PROTOCOL)

The protocol has an identical structure for all 3 interface types: RS-232, SPI and I²C. Each data transfer is

embedded in a fixed frame with a checksum (protocol package). The EA eDIP128-6 acknowledges this

package with the character <ACK> (=$06) on successful receipt or <NAK> (=$15) in the event of an incorrect

checksum or receive buffer overflow. In the case of <NAK>, the entire package is rejected and must be sent

again. Receiving the <ACK> byte means only that the protocol package is ok,

there is no syntax check for the command.

Note: It is neccessary to read the <ACK> byte in any case. If the host

computer does not receive an acknowledgment, at least one byte is lost. In

this case, the set timeout has to elapsed before the package is sent again.

The raw data volume per package is limited to 255 bytes (len <=255).

Commands longer than 255 bytes (e.g. Load image ESC UL...) must be split

up between a number of packages. All data in the packages are compiled

again after being correctly received by the EA eDIP.

DEACTIVATINGTHE SMALL PROTOCOL

For tests the protocol can be switched off with an L-level at pin 17 = DPROT.

In normal operation, however, you are urgently advised to activate the

protocol. If you do not, any overflow of the receive buffer will not be

detected.

Command/data to the display

Request for content of send buffer

BUILDINGTHE SMALL PROTOCOL PACKAGES

<DC1> = 17(dez.) = $11

<ACK> = 6(dez.) = $06

len = count of user data (without <DC1>, without checksum bcc)

bcc = 1 byte = sum of all bytes incl. <DC1> and len, modulo 256

The user data is transferred framed by <DC1>,

the number of bytes (len) and the checksum

(bcc). The display responds with <ACK>.

The command sequence <DC2>, 1, S, bcc

empties the display’s send buffer. The display

replies with the acknowledgement <ACK> and

begins to send all the collected data such as

touch keystrokes.

<DC2> = 18(dez.) = $12

1 = 1(dez.) = $01

S = 83(dez.) = $53

<ACK> = 6(dez.) = $06

len = count of user data (without <DC1>, without checksum bcc)

bcc = 1 byte = sum of all bytes incl. <DC1> and len, modulo 256