MIKROE-127 mikroElektronika, MIKROE-127 Datasheet - Page 2

• Manufacturer Part Number: MIKROE-127
• Description: Daughter Cards & OEM Boards PORT EXPANDER MCP23S ADAPTER BOARD
• Manufacturer: mikroElektronika

Specifications of MIKROE-127

• Rohs: yes
• Product: Port Expander
• Data Bus Width: 16 bit
• Description/function: Port Expander provides easy I/O port expansion using a standard serial interface such as SPI
• Interface Type: SPI
• Tool Is For Evaluation Of: MCP23S17
• For Use With: Development System

MikroElektronika
PORT Expander Additional Board
The PORT Expander additional board provides easy I/O port expansion using a standard serial interface such as SPI. Connection
with a development system is established by connecting 2x5 male connectors on the additional board to the appropriate port on the
development system. Depending on the development system in use, it is necessary to select one of three connectors supplied on
the additional board. For dsPIC development systems, the CN1 (dsPIC) connector is connected to the PORTF port. For AVR-8051
development systems, the CN2 (AVR-8051) connector is connected to the PORTB port. PIC development systems use the PORTC
port to establish connection with the CN3 (PIC) connector on the additional board. The PORT Expander board provides two additonal
ports PORTA and PORTB for the development system it is connected to.
The PORT Expander additional board uses SPI serial interface to communicate with the microcontroller provided on the development
system it is connected to. Additional ports receive/send data in parallel format, which means that it is necessary to convert it into
serial format. The MCP23S17 circuit, supplied on the additional board, is used to convert data received from 16 additional pins and to
transmit it to the microcontroller via two pins. The advantage of such conversion is obvious. Instead of 16 lines, the additional board is
connected to the microcontroller via only four lines known as data receive/transmit lines and two control lines.
The function of pins provided on connectors CN1, CN2 and CN3 is as follows:
MOSI
MISO
SCK
CS
INTA
INTB
Data transfer via MOSI and MISO lines is performed simultaneously in both directions. The MOSI line is used to transfer data from the
microcontroller to the port expander, whereas the MISO line is used to transfer data from the port expander to the microcontroller. The
microcontroller starts data transfer when the CS pin is driven low (0) by sending a clock signal (SCK).
2x5 male connector is used with
dsPIC development systems
2x5 male connector is used with
AVR-8051 development sysems
2x5 male connector is used with
PIC development systems
- Master Output, Slave Input (microcontroller output, MCP23S17 input)
- Master Input, Slave Output (microcontroller onput, MCP23S17 output)
- Serial Clock (microcontroller clock signal)
- Chip Select (data transfer enable)
- Interrupt pin
- Interrupt pin
Figure 1: PORT Expander additional board
Jumpers used to determine the
port expander’s hardware address
Additional port PORTA
Additional port PORTB