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µC-P1 Prototyping Board User Manual

Introduction

The µC-P1 prototyping board allows you to quickly and easily construct any custom electronics for the µConnect Bus. The board provides a dual µConnect interface for ease of daisy chaining, on board +5V regulator, I2C buffer, power status LED and prototype area. The µC-P1 allows any I2C compatible IC to be interfaced to the µConnect bus using only a few simple connections.

The µC-P1 board is high quality PCB with plated through holes throughout. The top of the board is laid out as a "colander" ground plane making the µC-P1 suitable for high speed/low noise applications.

µConnect Interface & Regulator

The µC-P1 provides a dual µConnect interface at the top of the board facilitating instant connection to other µConnect modules using standard RJ45 UTP patch cables. Power for the µC-P1 is derived from the µConnect Bus and regulated to 5V for on board use. A power status LED is used to indicate the presence of power on the bus. µConnect clock and data signals are buffered and made available as standard I2C clock (scl) and data (sda) signals.

The Prototype Area

The prototyping area consists of a grid of standard 0.1" pitch holes connected by vertical or horizontal tracks.

The 5V and Gnd rails run horizontally across the center of the board (marked + and - respectively ) allowing convenient power distribution to ICs. Additional access to +5V & Gnd is available beside the I2C buffer and beside the voltage regulator. Unregulated power is available at a single point (marked *) beside C2.

Access to the I2C signals is available beside the I2C buffer and are marked scl (I2C clock) and sda (I2C data) respectively. These signals have built in pull up capability and may be connected directly to any I2C compatible chip.

Holes on each side of the power rails are linked vertically for ease of signal distribution. An additional connection area is provided at the bottom of the board to facilitate external connectors.

 

 

 

 

Making the connection

While the µC-P1 can be used in many ways, it has been specifically designed to use a "top of board" wire-wrap technique. Connections are made on the top of the board between soldered in square pin headers using a standard wrapping tool. Each header pin can accommodate up to two wrap connections.

 

Mounting IC's

The most convenient mounting position for an IC is straddling the power rails. ICs should where possible be socketed. Because of the horizontal connections on each side of the power rails, you can now get access to the IC pins via the holes on each side of the chip. To use the suggested wire-wrap technique you should solder a row of square pin headers on each side of the IC, you can now make any required connections to the IC using a wire-wrap tool.

 

Mounting Axial Components

Axial components such as resistors and capacitors can be soldered directly into the board across the power rails. As with ICs, a square pin header soldered in adjacent to the component will allow easy wire-wrap connection to other components on the board.

 

Mounting Connectors

The huge variety of signal connectors available make it unfeasible to lay out a prototype board to facilitate them all. However with a little ingenuity most types of connectors can be accommodated. Many connectors have a standard 0.1" pitch configuration and so can be mounted directly onto the prototyping area. In particular the area at the bottom of the prototype grid is suitable for many connectors such as the popular Molex KK series or similar (as used as the power connector on the µFlash SBC, µS-BS2 µS-DD4).

Connectors with unusual pin layouts (such as D-type communications, Mini-DIN interface, RJ45 and RJ11 telecom) can be glued upside-down to the prototype board, wire-wrap connection can then be made directly to the pins of the connector. This is also the best way to make a connection to a standard IDC "ribbon cable" connector. Note that when using this technique, "Right Angle" versions of the connector should be chosen so that the pins point vertically when the connector is glued to the board.

 

 

 

 

Sample Application

Real time clock for the µConnect bus

Unlike the original µFlash876, the µFlash876B does not include a real time clock. This application note shows how a battery backed up RTC can be added to any system that supports µConnect by building a real time clock module onto a µC-P1 prototyping board.

The µC-P1 board provides all the connectors, signal buffering and power regulation necessary for the application, all we need to add is the circuitry for the I2C based RTC. The RTC chosen for the project was the DS1307, this is the same one used on the original µFlash876. We have included an LED on the RTC clock SQW/OUT pin to allow easy demonstration of the functioning unit.

The circuit shown below was constructed on the prototype area of a µC-P1 prototype board. You can see how only a few connections are required. It took less than 15 minutes to build the circuit onto a µC-P1.

Once complete the circuit can be connected to a µFlash876B with a µConnect cable (RJ45 UTP Patch Cable), after which it can be accessed by the µFlash as if it was on the local I2C bus.

It is worth noting that each µC-P1 board can support multiple local I2C chips, it would have been a relatively easy matter to also include (for example) EEPROM memory on this µC-P1 by also wiring a serial EEPROM (such as the 24LC64) to the SCL and SDA signals.

 
// CCS PIC C code to flash the LED on the RTC board
// Will also work with C2C, may require slight modification
// for other compilers
 
#include "uF876.h"  // include uFlash support code
#include "uConn.h"  // include uConnect support code
 
void main(void)
    {
    while(1)
        {
        uc_wstart(0x68);   // address the rtc (write)
        uc_write(0x07);    // ctrl reg @ 0x07
        uc_write(0x00);    // led on
        uc_stop();         // done
 
        delay_ms(500);     // delay half a second
 
        uc_wstart(0x68);   // address the rtc (write)
        uc_write(0x07);    // ctrl reg @ 0x07
        uc_write(0x80);    // led off
        uc_stop();         // done
 
        delay_ms(500);     // delay half a second
        }
    }
 

 

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