EA STARTEDIPTFT4 ELECTRONIC ASSEMBLY, EA STARTEDIPTFT4 Datasheet - Page 10

• Manufacturer Part Number: EA STARTEDIPTFT4
• Description: TFT Displays & Accessories Starter/Demoboard w/Touch USB prog
• Manufacturer: ELECTRONIC ASSEMBLY

Specifications of EA STARTEDIPTFT4

• Attached Touch Screen: Yes
• Background Color: White
• Interface: I2C, SPI, RS-232
• Interface Type: RS-232, I2C, SPI
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: - 20 C
• Operating Temperature Range: - 20 C to + 70 C
• Supply Voltage: 5 V
• Touch Panel: Touch Panel
• Viewing Area (w X H): 53.86 mm x 95.04 mm
• Module Size (w X H X T): 71 mm x 107 mm x 12 mm
• Backlighting: LED
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

EA eDIPTFT43-A
Page 10
DATA TRANSFER 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 eDIPTFT43-A 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 elapse 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
divided up between a number of packages. All data in the packages are
compiled again after being correctly received by the EA eDIPTFT43-A.
DEACTIVATING THE 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.
BUILDING THE SMALLPROTOCOL PACKAGES
Command/Data to the display
<DC1> = 17(dec.) = $11
len = count of user data (without <DC1>, without checksum bcc)
bcc = 1 byte = sum of all bytes incl. <DC1> and len, modulo 256
Request for content of send buffer
<DC2> = 18(dec.) = $12
<ACK> = 6(dec.) = $06
len = count of user data (without <DC2>, without checksum bcc)
bcc = 1 byte = sum of all bytes incl. <DC2>, modulo 256
>
<
>
<
>
<
<
Clear display and draw a line from 0,0 to 479,271
<ACK>
<DC1> len
$11
$06
<DC1>
<ACK>
<DC2>
<ACK>
<DC1>
$0E
ESC
$1B
len
$44
len
D
1
$4C $1B
L
ESC
S
<ACK> = 6(dec.) = $06
1 = 1(dez.) = $01
$47
G
bcc
$44
D
data...
$00
Example to a complete data package
data...
0
$00
$00
0
S = 83(dez.) = $53
$00 $DF
479
bcc
$01 $0FE $01
271
bcc
bcc
$60
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 the begins to send all the collected data
such as touch keystrokes.
void SendData(unsigned char
{
}
SendByte(0x11);
SendByte(len);
SendByte(bcc);
unsigned char
for(i=0; i < len; i++)
bcc = 0x11;
bcc = bcc + len;
{ SendByte(buf[i]);
}
bcc = bcc + buf[i];
„C“ source code to transmit a data package
i, bcc;
ELECTRONIC ASSEMBLY reserves
the right to change specifications
without prior notice. Printing and
typographical
// Send DC1
// Send data length
// Send buf
// Send checksum
*buf,
unsigned char
errors
reserved.
len)