gen
4 Display Module Series gen4-uLCD-24PT - 2.4”
©
2017 4D SYSTEMS Page 7 of 22 www.4dsystems.com.au
4.
Hardware Interface - Pins
This section describes in detail the hardware interface
pins of the device.
4.1.
Serial Ports – TTL Level Serial
The Picaso Processor has two dedicated hardware
Asynchronous Serial ports that can communicate with
external serial devices. These are referred to as the
COM0 and the COM1 serial ports.
The primary features are:
•
Full-Duplex 8 bit data transmission and
reception.
•
Data format: 8 bits, No Parity, 1 Stop bit.
•
Independent Baud rates from 300 baud up to
600K baud.
•
Single byte transmits and receives or a fully
buffered service. The buffered service feature
runs in the background capturing and buffering
serial data without the user application having to
constantly poll any of the serial ports. This frees
up the application to service other tasks.
A single byte serial transmission consists of the start
bit, 8-bits of data followed by the stop bit. The start
bit is always 0, while a stop bit is always 1. The LSB
(Least Significant Bit, Bit 0) is sent out first following
the start bit. Figure below shows a single byte
transmission timing diagram.
COM0 is also the primary interface for 4DGL user
program downloads and chip configuration (PmmC
programming). Once the compiled 4DGL application
program (EVE byte-code) is downloaded and the user
code starts executing, the serial port is then available
to the user application. Refer to Section 5. ‘Firmware
/ PmmC Programming’ for more details on this
subject.
TX0 pin (Serial Transmit COM0):
Asynchronous Serial port COM0 transmit pin, TX0.
Connect this pin to external serial device receive (Rx)
signal. This pin outputs at 3.3V Level.
RX0 pin (Serial Receive COM0):
Asynchronous Serial port COM0 receive pin, RX0.
Connect this pin to external serial device transmit (Tx)
signal. This pin is native 3.3V level, but 5.0V tolerant.
TX1 pin (Serial Transmit COM1):
Asynchronous Serial port COM1 transmit pin, TX1.
Connect this pin to external serial device receive (Rx)
signal. This pin outputs at 3.3V Level.
RX1 pin (Serial Receive COM1):
Asynchronous Serial port COM1 receive pin, RX1.
Connect this pin to external serial device transmit (Tx)
signal. This pin is native 3.3V level, but 5.0V tolerant.
Please
refer
to
the
'PICASO-4DGL-Internal-
Functions.pdf' document for more information.
Serial ports output at the level of TTL 3.3V, however
are 5V tolerant, so can accept communications from
5V devices.
4.2.
General Purpose I/O
There are 13 general purpose Input/Output (GPIO)
pins available to the user. These are grouped as IO1
IO5 and BUS0
BUS7. Power-Up Reset default is
all INPUTS.
The 5 I/O pins (IO1
IO5), provide flexibility of
individual bit operations while the 8 pins (BUS0
BUS7), known as GPIO BUS, serve collectively for byte
wise operations. The IO4 and IO5 also act as strobing
signals to control the GPIO Bus. GPIO Bus can be read
or written by strobing a low pulse (50ns duration or
greater) the IO4/BUS_RD or IO5/BUS_WR for read or
write respectively. For detailed usage refer to the
separate document titled:
“PICASO-4DGL-Internal-Functions.pdf”
IO1-IO5 pins:
General purpose I/O pins. Each pin can be
individually set for INPUT or an OUTPUT.
Power-Up Reset default is all INPUTS. Digital GPIO
can source/sink 4mA.
For more information see the Specifications section
of this datasheet.
