PCB-RELAY8 BUSBOARD

Document overview

  • Manufacturer or author: Provided By www.digicamel.com(free datasheet download site)
  • PDF pages: 3

Technical content

Features

A bare PCB to build a relay board with 8 DPDT relays. Each relay has up to four 3 pin terminal bloc ks to connect to the relay contacts. Can be controlled via an I2C interface or 8 logic lines. UEXT connector used for I2C connection. Can be used with 5V, 9V or 12V Omron G5V series relays with 2 Amp contacts. The supply voltage must match the relay volt age. Separate logic supply required for I2C. Bare PCB only (unpopulated, no parts provided). BOM and schematic available for download. Mostly thru hole construction allows for easy assembly (I2C output port is SMT). Details The RELAY8 is an output board providing 8 DPDT relays for microcontroller projects. Each relay has two switches with NO and NC contacts (Normally Open and Normally Closed).

BusBoard Prototype Systems Built for designers www.BusBoard.com sales@busboard.com BPS DAT (PCB RELAY8) 0001 Rev 0.10 Datasheet.doc Removable 5.08mm (0.2 inch) terminal blocks are used to connect circuitry to the relays. Each relay has two s witches, and each switch has two 3 pin terminal blocks that can be installed to provide an easy way to connect multiple wires to each contact. The RELAY8 board can be built to be controlled by 8 logic signals or an I2C interface. A 2x8 header is used to connect to the inputs with a 16 pin ribbon cable for the logic level version. An Olimex style UEXT 2x5 header is used for the I2C option. UEXT is an open standard developed by Olimex providing 3 Volt I2C, SPI, and USART expansion on one connector. A 10 pin ribbon cable is used to connect to dev boards with UEXT connectors. The power input connector can be a coaxial barrel connector, a 2 pin terminal block, or a 2 pin MTA 100 connector, or 0.1" spacing header. This is an unpopulated board and no parts a re included. The BOM (bill of materials) and schematic diagram are available at http://www.busboard.us/products/PCB RELAY8/ to construct the circuit. Soldering is required and prior experience wi th electronic assembly is recommended. A PCB soldermask helps prevent solder bridges on tracks and a silkscreen legend provides part locations. Construction The construction is complete ly thru hole for the parallel port version providing easy assembly, maintenance, and modification. The I2C version uses a SMT output port IC and a 0805 capacitor and resistors (it’s still easy to solder). When assembling the board, install the SMT components first (if any). Install the thru hole components from shor test to tallest to make it easier to keep the parts inserted when soldering. Hint: Insert the thru hole parts of a particular height, place a stiff piece of cardboard over the board, and turn it over using the cardboard to hold the parts in place. Then y ou can solder them. GPIO Parallel P o rt Option The parallel port connector uses an 8 bit GPIO port from the microcontroller to control the 8 relays. The signals are carried on a 16 pin ribbon connector to the 2x8 shrouded connector J29 The connector has the same pinout as the GPIO headers on BPS development boards and baseboards. The Vlogic power is separate from the Vrelay power to allow the relays to be driven at a different voltage, or to provide a higher current supply for the relays. Vlogi c and Vrelay can be connect ed if needed using jum per JU1. The GPIO 2x8 connector J29 pinout is as follows: Signal Function Pin Pin Signal Function Relay +5V Relay +3V3 (not connected) Relay Uncommitted Pin Relay Uncommitted Pin Relay Uncommitted Pin Relay Uncommitted Pin Relay Uncommitted Pin Relay Ground

BusBoard Prototype Systems Built for designers www.BusBoard.com sales@busboard.com BPS DAT (PCB RELAY8) 0001 Rev 0.10 Datasheet.doc I2C Driver Option An I2C driver can be ins t alled to control the relays instead of using

8 GPIO lines

connector options are provided, a 4 pin connector J46 or a 2x5 UEXT header J55. The C driver IC is PCF 8574T which is available from NXP and Texas Instruments. The I2C address can be selected using jumpers JU2, JU3, and JU4. pin I2C Connector J45 J provid e s a 4 pin connection for the I2C interface A Tyco MTA 100 type polarized connector is typically used, but the 0.1” pin spacing allows other connector types to be fitted as well. The SMT pull up resistors must be installed on the base board or on a peripheral board for the I2C to function. Typically they are on the microcontroller board, al lowing multiple peripheral boards to be connected. The pull up resistors R21 and R22 are not fitted in this case The pin I2C connector signals are as follows: Pin Name

Description

+5V (or +3.3V) Power to I2C Driver Power to Relay8 UEXT Connector J55 The Universal EXTension Connector (UEXT) is an expansion connector standard created by Olimex Ltd. ( www.Olimex.com ). It provides an asynchronous serial port (USART), SPI and I2C all on the same connector. Peripheral modules for UEXT are available from Olimex (and stocked at www.Mouser.com as well as from other suppliers. The R elay8 uses only the I2C signals and power and ground to power Vlogic for the Driver IC (pins 1,2,5,6) The UEXT interface standard uses a 2x5 polarized header with 0.1” spacing. Modules connect to the UEXT connector with a 10 pin ribbon cable. The UEXT pinout is as follows: Direction Signal Function Pin Pin Signal Function Direction Output +3.3 Volts GND Output from MCU USART TX USART RX Input to MCU Output I2C SCL I2C SDA Bi directional Master In Slave Out SPI MISO SPI MOSI Master Out Slave In Master Out Slave In SPI SCK SPI SSN Master Out Slave In Most UEXT modules are designed for 3.3V operation only. Therefore, no +5V power option is provided on most UEXT headers.