Qty ID P/N Package Description =============================================================================== 1 1WIRE 3 position t-hole 3.5mm pitch screw terminal block 1 BAT1 KEYELCO3001 t-hole 12mm battery holder 1 CR2022 3V coin cell battery 5 C1-C5 1uF SMD3528 Tantalum chip capacitor 3 C6-C8 100nF SMD0805 Ceramic chip capacitor 2 C9, C10 100nF t-hole Ceramic capacitor 2 C11, C12 100uF t-hole Al Electrolytic capacitor 35V 2 C13, C14 1n2F SMD0805 Ceramic chip capacitor1 1 D1 1N4007 t-hole Diode 1 D2 1N4148 t-hole Signal diode 1 IC3 MAX232SE SO16 Maxim RS232 Line Driver 1 IC4 7805DT TO252 5V voltage regulator 1 IC5 ATMEGA168-PU DIL28 Atmel AtMega168 10Mhz or 20MHz 1 J1 DCJ0202 t-hole DC power jack 1 LCD1 20x4 LCD Hitachi HD44780 based LCD dsp 1 16 x 0.050 sqr female header (install on board for LCD) 1 16 x 0.050 sqr male header (install on LCD) 1 R1 10K SMD0805 Chip resistor 1 R2 A/R t-hole Pull-up resistor 4K7 to 10K 2 R3-R4 470R SMD0805 Chip resistor 1 R5 10K SMD5X Trim potentiometer 4 S1-S4 B3F-10XX t-hole Omron momentary pushbutton 1 X1 IDC6 t-hole IDC 3x2 Female socket a 3x2 0.050 sqr dual header can be used instead 1 X4 F09D sldr-tail Sub-D 9-pin female connector Optional Real Time Clock 1 IC2 DS2415P TSOC6 Dallas/Maxim 1-Wire RTC Chip 1 C15 100nF SMD0805 Ceramic chip capacitor 1 R6 10K SMD0805 Chip resistor 1 X3 TC38 32.768KHz watch crystal (6pF load capacitance Citizen CMR200TB32.768KDZBTR or equiv) 1 BAT1 KEYELCO3001 t-hole 12mm battery holder 1 CR2022 3V coin cell battery Optional Brownout Protection 1 U1 MCP120T-460I/TT SOT233 Microchip uC 4.6V supervisor Miscellaneous 9V DC 500ma wall wart - center conductor should be positive. Turned pin breakaway IC socket strips Construction Notes =============================================================================== This board is made with a mixture of through-hole and SMD components to facilitate construction using hobbyist techniques (i.e. toner transfer) and minimize the number of drilled holes and still keep the number of vias at a manageable level. It is suggested to socket IC5 using turned pin socket strips. These strips expose a small amount of the pin above the board to allow soldering the connections on the component side. Remove two pins from some additional socket strip and use to socket resistor R2. This is a pull-up resistor for the 1-wire bus and may need to be adjusted based on the number of devices connected. The components for the RTC and brownout protection can be left off without harm. Solder jumper SJ1 is provided to allow disabling the RTC for testing if it is installed. Start construction by soldering, on both sides of the board, short jumpers into the 8 vias, and the two socket pins for R2. Next install the 5V regulator, IC4, diodes D1 and D2, the power jack, and capacitors C9, C10, C11, and C12. Be sure to solder C9, C10, and the rear tab on the power jack on the component side as well as the bottom of the board. Make sure the tab of IC4 is securely soldered. Before proceeding further, apply power, and verify +5V at the R2 socket nearest D1 and the power jack, as well as IC5 pins 7 and 20. Disconnect power and install IC2, IC3 and U1. Next add the breakaway socket strips for IC5 (or install IC5 directly on the board) making sure to solder both sides. Then solder all the SMD resistors and capacitors including the LCD contrast trim pot, R5. Add the four pushbuttons, again soldering both sides. Install the 1-Wire screw terminals, LCD female header, the clock crystal. Before installing the battery holder, tin the three negative battery contacts on the component side of the board. Finally, add the IDC connector X1 if planning to program the uC in-circuit, and the DB9 connector for RS232. The DB9 connector is installed with the PCB inserted between the two rows of solder tail pins. Finally, bridge jumper SJ1 with solder if you want to enable the RTC. Clean the board with alcohol to remove the flux residue. Secure the RTC crystal, if installed, with hotmelt glue or adhesive - do not solder it to the ground plane. Install IC5 and R2 and connect your DS18x20 sensors to the screw terminals (+5V is nearest the power jack, ground is nearest the LCD connector and 1-Wire data is the center terminal). Connect a serial cable between the board and your computer, fire up your terminal program on the PC, and set the communication parameters to 19200,n,8,1. Apply power to the board, and you should be good to go!