SBC44B with RS232 interface, sockets for RTC, EEPROM

SBC44B with RS232 interface, sockets for RTC, EEPROMIntroduction The SBC44B is an embedded Single Board Computer (SBC) for the PIC16 and PIC18 family of microcontrollers. It has a RS232 interface assembled, and sockets for the following I2C chips: RTC , for example the DS1307 EEPROM, for example the 24LC256 or 24LC512 (64 kbytes). RS485 interface driver, for example the MAX485, SP485 CAN BUS driver, for example the MCP2551 . Secondary 8 pin PIC running software that emulates an I2C slave device. Fitted

Introduction

The SBC44B is an embedded Single Board Computer (SBC) for the PIC16 and PIC18 family of microcontrollers. It has a RS232 interface assembled, and sockets for the following I2C chips:

• RTC , for example the DS1307
• EEPROM, for example the 24LC256 or 24LC512 (64 kbytes).
• RS485 interface driver, for example the MAX485, SP485 ...
• CAN BUS driver, for example the MCP2551 .
• Secondary 8 pin PIC running software that emulates an I2C slave device.

 Fitted with a PIC16F877 and a 20MHz crystal.

The 32.768 kHZ crystal for the RTC is already assembled. All that is needed for the RTC to work is for a RTC chip to be plugged in. The board is also shipped with a 5 pin 3.81mm terminal block plug that plugs into the boards terminal block header - as shown in the above photo.

The RS232 interface uses the 9 pin Sub-D connector (DTE). The 5 pin phoenix connector can be configured for RS485 or CAN BUS. When configured as a RS485 interface, the PIC chip's internal USART will be used for the RS485 interface, and the RS232 interface has to be driven by software. When configured as a CAN BUS a PIC chip with an internal CAN peripheral has to be used, like the PIC18F458 for example.

It has been optimized for any 44 pin PLCC PIC chip with an USART and I2C hardware peripheral, like the:

• PIC16C65, PIC16C67
• PIC16F74, PIC16F747, PIC16F77, PIC16F777, PIC16F877(A)
• PIC18F452, PIC18F458, .....
• Many more 44 pin PLCC PIC chips with USART and I2C peripherals.

This is only because the above mentioned chips have internal USARTs and I2C peripherals, which are connected to the serial drivers and I2C chips on this board. It can however also be used with most other 44 pin PLCC PIC chips , as long as their power, reset(MCLR) and oscillator pins are situated in the same place as the chips listed above. The only difference is that if it hasn't got a hardware USART or I2C peripheral, it will have to be done with software on the PIC chip.

Features
Is part of our MicroX product range, meaning you can upgrade or expand it with any of the other MixroX products.

Modular, it has the following MicroX connectors Daughter Board connector.

Compact Daughter Board connector.

Frontend connector

• Conforms to standard MicroX Main Board dimensions (97 mm wide and 54mm high) . For details see
• Assembled with High Quality, Industrial Temperature components - electrolytic capacitors used are extra long lifetime rated!
• Diode protected 2.1mm power connector for a standard DC transformer.
• Wide operating voltage range from 7 to 30V.
• On board 15kV ESD protected RS232 interface. Assembled with industrial temperature range interface driver chip.
• Sub-d 9 pin male connector (DTE configuration) with ground and RS232 Tx and Rx signals.
• 5 pin 3.81mm terminal block connector with RS485 or CAN BUS signals (when interface drivers are assembled), ground and external power.
• The power pin on the 5 pin terminal block connector can be connected to the boards unregulated power supply (the input of the 2.1mm power connector) via a strap. This can be used to: Provide power for all other boards daisy chained to this one. For this to work this board must be powered via its 2.1mm power connector! It will supply power to all other boards daisy chained to it.
• Obtain power for this board. In this case no power has to be supplied via the 2.1mm power connector. It will obtain it's power via the 5 pin terminal block connector.
• Power LED to indicate when device is powered.
• LED connected to B6 via high impedance resistor (2k2). Can be used by user application, and does not interfere with in circuit serial programming.
• Two pin connector (2 pin 2.54mm) for external battery for the RTC.
• Socket for a I2C Serial EEPROM to be fitted. For example the 24LC256 (32 kbytes), 24LC512 (64 kbytes).....
• Socket for a RS485 (SP485, MAX485...) or CAN BUS (MCP2551) interface driver chip to be fitted.
• Socket for a I2C bus RTC (DS1307 for example) chip to be fitted, the 32kHZ clock crystal is already assembled.
• Socket for a secondary 8 pin PIC chip to be fitted.
• Has a standard MicroX ICSP (In Circuit Serial Programming) connector - CPU can be programmed in circuit. Details see here.
• Can be use with UK 12v PSU.