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SBC Hardware: Main | SBC Schematic/Parts List | Technical Details | All pages in PDF format
SBC In-System Programming: Information | VisISP-52 ISP Application
SBCMON Monitor/Operating System: Main Page | Manual
SBCMON-based Software: SBCMON Monitor | Keypad Demo | LCD Echo Demo | Hardware Clock | Software Clock
SBCMON-based PS/2 Software: PS/2 Comm Monitor | PS/2 Keyboard | PS/2 Mouse

This page includes the schematics for the SBC. You may build a functioning version of the SBC by building based on these schematics. Click on each schematic page for a full-size version.

Microcontroller & Memory Latch

Memory (RAM & EPROM)

Memory-Mapped LCD & Keypad

Power & Misc.

In-System Programming (ISP) Schematic

Bill of Materials

The following parts are needed to build the SBC described above:

Reference Quantity Part Digikey Part Number Datasheet
C1-C14,C24,C25 16 0.1uF ceramic capacitor 1338PH-ND  
C15,C23 2 10uF electrolytic capacitor P5134-ND  
C16-C19 4 1uF electrolytic capacitor P10312-ND  
C20,C21 2 27pF ceramic capacitor P10797-ND  
C22 1 1000uF electrolytic capacitor P10253-ND  
C26 1 100uF capacitor P11198-ND  
D1-D4 4 1N4001 diode 1N4001GICT-ND  
D5 1 Red LED 404-1090-ND  
D6 1 Yellow LED 404-1092-ND  
J1 1 2.1mm power connector CP-202A-ND/CP-102AH-ND  
J2 1 DB25 male conector A23285-ND  
J3,J4 2 14-pin Female Header S4207-ND  
J5 1 8-pin Female Header S4008-ND  
J6 1 DB6 DB9 female RS232 A23303-ND  
J7-J12 6 8-pin SIPs    
JP1 1 2-pin jumper    
JP2-JP6 5 3-pin jumper    
R1,R7 2 330 P330BACT-ND  
R2 1 220 P220BACT-ND  
R3 1 10K Variable Resistor 3362U-103-ND  
R5,R6,R8 3 10K P10KBACT-ND  
R4 1 100 P100BACT-ND  
RN1 1 6.8k 6-pin resistor network 750-61-R6.8K-ND  
SW1,SW2 2 Momentary push button, normally open P8006S-ND  
U1 1 Atmel AT89S8253 AT89S8253-24PI-ND Datasheet
U2 1 74LS573 octal latch 296-1596-5-ND or TC74HC573AP-ND Datasheet
U3 1 27C64 UV EPROM (optional) 497-1685-5-ND Datasheet
U4 1 62256 8x32k RAM (or 6264) 428-1080-ND Datasheet
U5 1 74LS138 3x8 decoder/MUX 296-1639-5-ND Datasheet
U6 1 74LS08 Quad 2-Input AND Gate 296-1633-5-ND Datasheet
U7 1 74LS04 Hex Inverter 296-1629-5-ND Datasheet
U8 1 74LS32 Quad 2-Input OR Gate 296-1658-5-ND Datasheet
U9 1 74HC541 Octal Buffer/Driver 296-12813-5-ND Datasheet
U10 1 MAX232 Dual RS232 Driver/Receiver 296-1402-5-ND Datasheet
U11 1 74LS125 Quad Tri-State Buffer Active Low 296-1638-5-ND or 296-8386-5-ND Datasheet
U12 1 74HC126 Quad Tri-State Buffer Active High 296-8221-5-ND Datasheet
U13 1 DS1307 real time clock (RTC) DS1307-ND Datasheet
U14 1 AT25010A 128x8 Serial EEPROM AT25010A-10PI-2.7-ND Datasheet
U15 1 (OMIT--Don't use) MN13811 4.6V Reset Supervisor   Datasheet
U16 1 LM7805 5V voltage regulator 296-1974-5-ND Datasheet
X1 1 11.0592 MHz crystal X139-ND  
X2 1 32.768 kHz crystal 300-1002-ND  
  1 40-pin IC Socket A9440-ND  
  2 28-pin IC Socket A9428-ND  
  2 20-pin IC Socket A9420-ND  
  2 16-pin IC Socket A9416-ND  
  5 14-pin IC Socket A9414-ND  
  2 8-pin IC Socket A9408-ND  
  3 36-pin breakaway headers for J7-J12, JP1-JP6 WM6436-ND  
  1 16x2 LCD (left side 2x7 connector) 67-1770-ND or
  1 4x4 Keypad GH5003-ND  
  1 5W Heatsink for 7805 HS121-ND  
  1 Wall transformer, 12VAC 750MA, 2.1mm MT7119-ND  
  4 Bumpons Hemispheres .50X.14 Clear SJ5312-7-ND  


This is a list of potential solutions to problems that have been observed when constructing the SBC.

Problem: Everything works, but memory-mapped LCD hangs on 'M0I' command with LCD attached to J3. LCD does work when attached to J4 (direct-connect) and keypad and RAM also work.
Solution: Check pin 1 of U5 ('138).