Introduction: 1-wire Communication Interface
What is 1-Wire technology ?
The basis of 1-Wire technology is a serial protocol using a single data line plus ground reference for communication. A 1-Wire master initiates and controls the communication with one or more 1-Wire slave devices on the 1-Wire bus. Each 1-Wire slave device has a unique, unalterable, factory-programmed, 64-bit ID (identification number), which serves as device address on the 1-Wire bus. The 8-bit family code, a subset of the 64-bit ID, identifies the device type and functionality. Typically, 1-Wire slave devices operate over the voltage range of 2.8V (min) to 5.25V (max). Most 1-Wire devices have no pin for power supply; they take their energy from the 1-Wire bus (parasitic supply).
More about 1-Wire technology may be found on Maxim IC web pages.
1-Wire master communication interface
This instructable will show how to implement and use basic serial 1-Wire master communication interface like one show on picture (link).
Step 1: PCB for Project
This very modular PCB have two parts :
- 1-wire serial communication interface
- voltage regulator parts (using 78xx IC)
Pictures show both side of PCB.
PCB give possibility to use SMD or normal scale elements for accomplish functionality on most parts, and different connection options.
In some small number cases you may use 1-Wire device without any additional power supply. How ever when you try to do just little complicate things with more 1-Wire devices or with longer communication lines (wires) you will need to supply 1-Wire device with proper power.
Step 2: Parts for Project
Besides PCB we have 3 groups of elements :
Voltage regulator (5V)
- 7805 IC (T1)
- elco 100 uF (Cin)
- elco 10 uF (Cout)
- 2 pin screw terminal 200mil (P1)
- 2 x 2 pin 100 mil with cap connector (J1 & J2)
- Schottky 1N5407 (sD5)
- LED smd blue (LED)
- resistor 100 (R3)
1-Wire serial communication interface
- 2 x Schottky diodes (1N5818) (sD2 & sD1)
- 6.2V Zener diode (zD4)
- 3.9V Zener diode (zD3)
- resistor 1.5 k (R2)
- 1m flat 10 wire cable
- 2x5 pins header (RS232H)
- IDC 10 pin connector
- IDC 9 pin female D-sub connector
- 5 pin screw terminal 3.5 mm (1-Wire Bus)
Schematic for both part of project are in pictures.
Step 3: Step 1. Soldering Small SMD Parts (bottom Side of PCB)
First solder small SMD bottom parts LED and resistor R3 . This two item is part of 5V voltage regulator. Resistor R3 depend of LED you use calculated on follow formula :
R = (5 - LEDreV)/LEDI
LED orientation is defined with mark on board, and mark on bottom side of LED like is shown on picture.
Step 4: Step 2. Soldering Lower Top Parts
First solder parts of 1-Wire serial communication interface (R2, sD1, sD2, zD3, zD4) , then diode sD5 .
Picture show how to bend connection wire of elements to nicely fit on PCB. Also all mark on diodes fit to marks on PCB (shown on picture) for easy orientation.
Step 5: Step 3. Soldering Other Top Side Parts
First solder 2x5 pins header (RS232H) then two 2 pin 100 mil with cap connector (J1 & J2).
Next solder 5 pin screw terminal 3.5 mm (1-Wire Bus) and 2 pin screw terminal 200mil (P1).
Finally in my configuration I need to solder two shortcut wire. First at position SW which is dedicate for power switch (if you use some solder switch wire in that place) and second one on position P2 (like was shown on picture). This shortcut is needed because of power supply input terminal organization (more on picture) .
Step 6: Step 4. Soldering Other Bottom Side Parts
In this step we solder SMD elco 100 uF (Cin) and elco 10 uF (Cout) . Outline of bottom case of elco SMD is printed on PCB, and also polarity. Further more - on PCB coresponde with black mark on SMD elco case.
Step 7: Step 5. Soldering Voltage Regulator
Finally we solder voltage regulator 7805 (T1) on place, outline of case is printed on PCB.
Printed mark on PCB suggest orientation if you use other type of voltage regulator (In, GND, Out) .
Step 8: RS232 Connection Cable Using IDC Type Connector
Crimp 10 wire flat cable to IDC type 10 pin connector like is shown on picture. For other side we use IDC type 9 pin female D-sub connector like is shown on second picture. Cut wire number 10 (we use only 9 wires) and put marked wire (red on picture) on first position and crimp it.
ADDitional INFO: in some series of PCB 10 pin connector doesnt have proper order of wires for 9 pin D-sub connector (direct one2one order) and follow reorganization of wires is needed 1,6,2,7,3,8,4,9,5 . When you got PCB that is clearly marked
Step 9: Final Step: Power on and Use
If everything is done correctly , and all soldering is clean and proper, we only need power supply of 8V ~ 26V to be connected on P1 terminal wire connector (blue one). After connection blue led will be light.
Connecting 1-Wire device may be done using 1-Wire Bus terminal wire connector (Green one). Connection lids are follow :
1- + Unregulated voltage
2- +5V regulated voltage
4- 1-Wire DATA
5- NC line
RS232 IDC D-Sub connector need to be connected to PC. You may use any of 1-Wire connection software like digitemp or Java API and java library.
Also for more info you may read nice instructable, with similar content.
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