WWW8052 - Hardware

WWW8052 - The Very First Version of Web51

To create a "small" WWW server, all that is needed is a CPU, in our case a x51 clone, a LAN interface card originally intended for PCs, several small components such as an ISA connector, piece of breadboard, a few capacitors, perhaps several LEDs with appropriate resistors. Connect everything togegher, utter a few magic words, and it turns into a WWW server.

Impulse for this project was the July 99 issue of Circuit Cellar, where a $25 WEB SERVER based on AT90S8515 was described. Other, more or less elaborated constructions, are on the WWW as well - for example Gary Desrosiers' Embedded 10BaseT Ethernet, based on CS8900 by Crystal (Cirrus Logic).

Our construction uses a Micronet SP2020B LAN board with a NE2000 compatible controller RTL8019AS by Realtek. The board is connected to a 8052 compatible CPU, AT89C25 by Atmel, with 8kB of program memory and 256 bytes of RAM that also holds registers and stack. This processor clearly does not provide a lot of resources; however, beta firmware is a proof that it has enough for our purpose. Beta version code occupies close to 3 kBytes, controls the LAN card through a packet driver, supports ARP, ICMP, IP and TCP protocols. Software implements a simple WWW server and provides for monitoring and control of the remaining I/O pins (not used for communication with the LAN board) over WWW. In addition, it also allows telnet connections to control the serial port, acting like a LAN/RS232 converter.

WWW8052 Hardware - Prototype of Web51

The LAN board is one of many NE2000 compatibles. Its advantages include time-tested drivers available in source code. RTL8019AS is one of the modern "everything on a single chip" implementations of the NE2000 standard. It integrates 16 kBytes of SRAM, modulator and demodulator for the physical interface, Ethernet protocol controller, memory interface, and many other functions.

However, unlike CS8900, it does not contain input/output filters, so a hybrid transformer with low-pass filter is necessary. Its main advantage is the capability to operate in 8-bit mode. As the schematic (or the EAGLE version - www8052.sch) shows, we take advantage of this option.

The processor connects to the ISA bus as follows:

P0 creates data signals of the "ISA" bus

P2 is partially used to provide address signals (P2.0 až P2.4) and reset (P2.7)

P3.6 a P3.7 control reading and writing, taking advantage of the alternative HW function.

Prototype version uses a 14.74 MHz xtal for easy generation of frequencies needed for the serial port. If serial communication is not needed, another xtal may be used - preferably as fast as possible to decrease latency. Power consumption of the prototype averages approximately 1 W.

Since the network board's PnP function is not used and its configuration is stored in its EEPROM, it has to be configured in a PC with an appropriate utility before first use. The prototype uses 300h for the base address, hard-wired by connecting signals SA5 to SA19 of the ISA bus to GND or +5V. Boot ROM address and IRQ number do not matter as they are unused.

Version 2

The first single-board version. See the entire board: silk screen, component side, solder side. Sources for EAGLE (layout editor by CadSoft) are here.

AUI Network Interface

Interface in the following figure is simplified. It was used in version 2 and needs a converter with built-in isolation transformer for TX/RX/CD signals.

A full circuit should have such a transformer, e.g. 16PT-005A, connected between the AUI connector and the Web 51 board.

Simplified AUI interface Full AUI interface

AUI connector connects with a cable to JP2 (RX), JP3 (CD) and JP4 (TX) that connect to the respective outputs of the controller. Outputs TX+ and TX- need additional pull-down resistors of 270R (1%). AUI is powered from JP5 that connects to the input filtering capacitor C101. Therefore, power supply for the Web 51 must provide voltage as required by the AUI interface and enough current. Here is a photo of this version.

WWW8052 - List of components by component names

Components marked with (*) can be cannibalized from a network board, as most distribution channels don't provide RTL chips and 10BaseT transformers in single unit quantities.

Part     Value          Package

C1   (*) 1nF/2kV
C2   (*) 1nF/2kV
C3       10nF           SMD 0805
C4       10nF           SMD 0805
C5       180pF          SMD 0805
C6       180pF          SMD 0805
C7       33pF           SMD 1206
C8       33pF           SMD 1206
C9       33pF           SMD 1206
C10      33pF           SMD 1206
C11      22M/16VT
C12      22M/16VT
C13      22M/16VT
C14      22M/16VT
C15      22M/16VT
C16      10nF           SMD 1206
C101     47M/25VT
C102     100nF          SMD 1206
C103     100nF          SMD 1206
C104     100M/6.3VT
C105     100nF          SMD 1206
C106     100nF          SMD 1206
C108     100nF          ceramic capacitor
CON1     DB9            Cannon 9 pin FEMALE
CON2 (*) RJ-45          UTP RJ-45
CON3     pinhead 13x1   2.54mm spacing 
CON4     PWCON          power socket
D1                      LED diode
D2                      LED diode
D3                      LED diode
D4                      LED diode
D5       1N4001         diode
D6       1N4101         diode
D7       1N4001         diode
IC1      8052           8052 CPU / 89S8252
IC2  (*) RTL8019AS      network controller
IC3      MAX232         TTL/RS-232 convertor
IC4      7805           V-REG
IC5      AT24C512       serial EEPROM
Q1       14.74 MHz      QUARTZ
Q2   (*) 20MHz          QUARTZ
R1       49R9           SMD 0805
R2       49R9           SMD 0805
R3       10R            SMD 0805
R4       10R            SMD 0805
R5       1K0            SMD 1206
R6       1K0            SMD 1206
R7       27K            SMD 1206
R8       10K            SMD 1206
R9       10K            SMD 1206
R10      1K0            SMD 1206
R11      1K0            SMD 1206
TR1  (*) FC-22          10BaseT isolation transformer / filter

WWW8052 - list of components by values

Qty  Value                         Parts

2    10R                SMD 0805        R3, R4
2    49R9               SMD 0805        R1, R2
4    1K0                SMD 1206        R5, R6, R10, R11
2    10K                SMD 1206        R8, R9
1    27K                SMD 1206        R7
2    33pF               SMD 1206        C7, C8, C9, C10
2    180pF              SMD 0805        C5, C6
2(*) 1nF/2kV                            C1, C2
2    10nF               SMD 0805        C3, C4
1    10nF               SMD 1206        C16
4    100nF              SMD 1206        C102, C103, C105, C106
1    100nF              ceramic cap.    C108
5    22M/16VT                           C11, C12, C13, C14, C15
1    47M/25VT                           C101
1    100M/6.3VT                         C104
4                       LED diode       D1, D2, D3, D4
2    1N4001             diode           D5, D7
1    1N4101             diode           D6
1    14.74 MHz          QUARTZ          Q1
1(*) 20MHz              QUARTZ          Q2
1    8052               CPU 8052...     IC1
1(*) RTL8019AS          ethernet contr. IC2
1    MAX232             TTL/RS232 conv. IC3
1    7805               V-REG           IC4
1    AT24C512           serial EEPROM   IC5
1(*) FC-22              transf./filter  TR1
1    DB9        con. Cannon9 Female     CON1
1(*) RJ-45              RJ45            CON2
1    pinhead       13x1, 2.54mm spacing CON3
1    PWCON      power supply connector  CON4
1    PCB                Web 51