Experimental board for I2C-BUS; 8051 and AVR fam.

K51 AVR English Tech. Manual PDF format.

Ver.5.00 - Rel.. 05 September 2000

K51 - AVR board, on the left mounting a 13 mm Display, on the right mounting a 20 mm Display.

In an area as small as 145 cmq a set of resources that allow to embark on the learning and the experimentation of several kinds of contol modalities and interfacing are concentrated.



Serie of 7 Articles about K51-AVR card that show the various Hardware/Software possibilities of the same. These articles have been published on the Italian magazine Elettronica Flash and are available also in these following languages: English, Spanish, Portugues and Polish.

Concerning the special ICs so as RTC; Display Controller; Temperature Sensor and so on , their Data Sheets are available on our web site at: DATA SHEETs

General Considerations

Through K51-AVR board it is given the chance to have a well-known and documented hardware, both under a software and a hardware point of view, to undertake any learning path which, starting form simple experiments, can improve experience and application complexity, up to being able to handle, with complete mastery and great competence, the basic elements of micro-controllers based electronics.
Under the task to make a Clock Watch its several circuital elements will be introduced, providing the complete know-how to get the informations about their use and data sheets. This will be possible through giving the Internet addresses of the documents available.
A simple application example will be provided for each new integrated circuit introduced , to make it immediately usable.
Several examples, with increasing level of complexity, will allow to learn and apply the new concepts, giving a continuous and constant cultural improvement. After a relatively short time You will have acquired the knowledge the will allow You to approach even the hardest jobs in a sistematic way and using the correct method.


One of the most important features of K51-AVR is the possibility to use the new microprocessors PHILIPS 89C51Rxx or ATMEL 89C51Rxx and
compatible supporting In System Programming, that is the programmation of the device and Without the requirement of any External Programmer. Below are described the step that must be executed:

1) develop the application program using a software tool capable to generate executable code

2) connetct jumper J5 in position 1-2 and J6 in position 1-2

3) connect the programming tension (+12 V for 89CRx+ or +5 V for 89CRx2) to pin 3 of CN6

4) connect the RS 232 serial line to a free COM port on a personal computer

5) supply the board

6) program the FLASH EPROM internal to the Microprocessor using the specific program. The programs and their updates are available for download directly from their manufacturer's websites and, currently, are FREE of Charge.

7) turn off the board

8) disconnect the programming tension from CN6, connect J5 in position 2-3 and connect J6 in position 2-3 to enable the microprocessor internal ROM

9) supply the board again: the appliction progral is executed from internal FLASH EPROM

I S P reduces the total development cost, infact it eliminates the need to use EPROM, EPROM programmer, FLASH EPROM, etc. For further information about I S P programming please refer to the specific technical documentation by PHILIPS


Serial communication line of K51-AVR board is buffered in RS 232. By software almost all the parameters of the physical protocol can be set (baud rate, stop bit) programming CPU internal registers.
K51-AVR is provided with a second RS 232 driver that, when connected to two microprocessor pins not yet used, can build a software serial line through the BASIC 8051 commands. To make the connection easier please refer to connectors CN1 (TTL signals) and CN3 (RS 232 signals).


For the software, having to choice a language Easy, Efficent and possibliy Low Cost, we consider the MCS-Electronics BASIC Compiler and the Wickenhaeuser C Compiler as the ideal tool for such purpose. This compiler is available both for the extremly wide 8051 family and for the new and fast ATMEL RISC chips called AVR. The names of the versions are BASCOM-8051 and BASCOM-AVR for thr BASIC and µC/51 for the C Comiller. It is also remarkable the availability the Technical Manual in English.
To all the ones who, as in their right, want to "take a look to the real thing" we would wanto to remark that the DEMO version is downloadable for free directly from the site both for 8051 and for AVR. The only limit of DEMO version is the maximum size of the generated code (2K), which is largely enough to test the tool. In fact, we have been able to fit a wide set of examples in this size, including the Clock Watch. So You will be able to perform all the necessary tests before embarking on the building of any application.
Develop high quality software for any 8051 in ANSI C. The only limit of DEMO version is the maximum size of the generated code 8K!!!, which is largely enough to test the tool.

CPU Section

This section is made by the Reset circuitry, managed through a TL 7705, capable to generate both a RESET and a /RESET complemented signal; a key and a 3 pins jumpers to switch between 51 or AVR mode.
A Quartz and two sockets also belong to this section. The sockets may even be ZIF (Zero Insertion Force) type, capable to host the CPU in 20 pins and 40 pins format. For convenience in reperibility, there is also the possibility to use 24 pins ZIF sockets, also usually less expensive than the other ones.

Seial Communication Line

A comfortable 9 pins, male, 90 degreeses, D type connector makes available a standard serial communication line, made using a MAX 202 or a MAX 232.
This integrated circuit is available on only one of the two communication sections, the other one remains unused for future expansions.

I2C-BUS Inteface

Peripherals management simulating I2C-BUS through 2 I/O signals of the CPU:

I/O Devices and Signals

The following devices are available for experimentations:

Digital Watch

The circuitry used to make the watch includes RTC PCF 8583; 7-segments display controller SAA 1064; four keys and one BUZZER. The circuit is controlled through the I2C-BUS protocol created by Philips and widely used in several fields.
Such communication protocols involves only two wires to perform informations exchange between both peripheral devices and intelligent systems. The BASCOM Compiler allows to use the not quite easy I2C-BUS through simple "High Level" instructions, without any need to know or undestand the protocol itself.
For who wants to learn more about this protocol we suggest to read the complete and clear treatment made by Philips in its Data-Book.
To emphasize the flexiblity of I2C-BUS protocol it is enough to remark that, to test the above introduced circuitries, it is possible to employ the very comfortable GPC® F2 board, already purchased or self-made by several people, that can be used to debug and test all the example programs.



C1, C8, C9, C11, C12, C13 , C15, C16, C22, C27, C28 C29, C30, C33, C32, C46, C49 = 100nF Multilayer
C2, C10 , C14, C23, C31, C45, C48 = 22µF 6v Tantalio
C3 , C4, C5, C6, C7, C34, C35, C36, C37, C38, C39, C40 C41, C42, C43, C44 = 100nF 50v poliester
C17 , C18, C19, C20, C47 = 1 ÷ 2,2µF 16v Tantalio
C21, C23 = 22pF ceramic
C24, C25 = 33pF ceramic
C26 = 300pF ceramic


R1, R3 , R12 = 680 Ohm 1/4w
R2 = 10 Ohm 1/4w
R4, R5, R6, R7, R8 = 4k7 Ohm 1/4w
R9 = 0
R10 = 470 Ohm 1/4w
R11, R13 = 18 Ohm 1/4w
RR1, RR2 , RR3 , RR4, RR5 = SIL 4k7 Ohm 9+1 pin


D1, D2, D3, D4 = 1N4148
Q1, Q2 = BC547
IC1 = PCF 8574A
IC2 = PCF 8591
IC3 = DS 1621
IC4 = 24C01/02/04/08
IC5 = TL 7705
IC7 = PCF 8583
IC8 = 89C1051/2051/4051 AVR 90S2313 etc.
IC9 = 8xC51/52 ecc AVR 90S4414/8515
IC10 = SAA1064
IC11 = LM336 2,5v
IC12 = TLC2543


CN1, CN3, CN4 = 20 way
CN2 = 9-way sub-D, 90° F
CN5 = 10 way screw, 2,54mm
CN6 = 8 way screw, 2,54mm


IC1, IC2 , IC6 = 16 pin
IC3 , IC4 , IC5 , IC7 = 8 pin
IC8 = 20 pin (or 24 pin) + Textool
IC9 = 40 pin + Textool
IC10 = 24 pin
IC11 = -----
IC12 = 20 pin


J1 , J3 , J4 = 2 way strip
J2 , J5 , J6= 3 way strip


T1 , T2 , T3, T4= pushbutton, 1 mark contact
BT1 = Lithium CA2032
RV1 = trimmer 4k7 Ohm
RV2 = trimmer 10k Ohm
QZ1 = quarz crystal 32,768 KHz
QZ2 = quarz crystal 11,0592 MHz
BZ1 = buzzer 10mm, 5Vdc
P1 = Reset, pushbutton, 1 mark contact
LD1 = LED 3mm Green
LD2 = LED 3mm Red
LD3 = LED 3mm Yellow
DY1 or DY5= SA52-11 display / SA08-11 display
DY2 or DY6= SA52-11 display / SA08-11 display
DY3 or DY7= SA52-11 display / SA08-11 display
DY4 or DY8= SA52-11 display / SA08-11 display

Last Up-dated at September 24, 2011

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