Component: One Wire (Comms: Interface)
| Author | Matrix Ltd |
| Version | 1.3 (Release) |
| Category | Comms: Interface |
Contents
One Wire component
Low level routines for controlling or interacting with a standard one wire interface.
Examples
Device Scanning
To get started with one wire devices it is often useful to collect the unique device serial number for each and every one wire device you are going to connect to your bus.
For example if you have a bus with two temperature sensors connected it is useful to know which sensor is which. Sensor A is monitoring temperature A and sensor B is monitoring temperature B. The only way to tell which is which is to use the serial number.
Here is a program that scans for devices on a one wire bus and outputs the device count and serial numbers using a LCD.
Here is the same program but this time the device count and serial numbers are output using a UART such as on an Arduino or ESP32.
To use the example simply connect a single device to the one wire bus and make a note of the reported serial number. This serial number can then be entered into the specific one wire component and used to ensure you are communicating with the device you think you are.
Single Device
Here is an example program to read a single DS18S20+ one wire temperature sensor device using a 16F1937 device. The DS18S20+ is connected to pin C0 and to display the temperature there is a LCD connected to PortB.
Single One Wire Demo
Multiple Devices
Here is an example program to read multiple DS18S20+ one wire temperature sensor devices connected to pin C0 and display the temperature of the selected sensor onto a LCD connected to PortB. Switches connected to pins A0 and A1 allow the currently active sensor to be changed. A0 increases the sensor index, A1 decreases the sensor index.
Multiple One Wire Demo
Downloadable macro reference
DS1820_StartConversion
DS1820 device specific function
Commands all sensors to start a temperature conversion
Parameters
- This macro has no parameters
Return value
ReceiveByte
Receives a byte from the one wire bus a bit at a time
Parameters
- This macro has no parameters
Return value
TransmitByte
Transmit a byte to the one wire bus a bit at a time
Parameters
- BYTE Command
Return value
- This call does not return a value
GetPadByte
Returns a byte from the last read scratchpad at position index. The index byte can go from 0 - 8 to reference the 9 individual scratchpad bytes.
Parameters
- BYTE Index
- Select which pad byte to use 0-8
Return value
BusReset
Issue a 'ping' on the bus. If there is at least one sensor on the bus then it will generate a presence pulse.
Returns 0 if a presense pulse was detected
Returns 1 no device was detected
Parameters
- This macro has no parameters
Return value
ScanBus
Scans the one wire bus to detect all devices
Parameters
- This macro has no parameters
Return value
GetDeviceCount
Returns the number of detected devices
Parameters
- This macro has no parameters
Return value
GetIDByte
Returns byte ectet of the 64-Bit lasered ROM code, 255 on error
Parameters
- BYTE device
- BYTE octet
Return value
DS1820_ReadScratchpad
Reads the scratchpad of the currently selected device
Parameters
- This macro has no parameters
Return value
ReadDevice
Reads the temperature of the device at location count in the id array
Parameters
- BYTE count
Return value
DS1820_GetTemp
Returns the two byte value of the temperature sensor
Parameters
- This macro has no parameters
Return value
Simulation macro reference
This component does not contain any simulation macros
Property reference
One Wire Pin
This property is of type Single digital pin and can be referenced with the variable name oo_pin.
I/O pin used to host one wire bus.
CRC Enabled
This property is of type True or false and can be referenced with the variable name crc_en.
Sets the CRC bit based error detection on or off. (cyclic redundancy check)
Label
This property is of type Line of text and can be referenced with the variable name label.
Label to draw on the GUI object for identification
Injector
This property is of type Fixed list of ints and can be referenced with the variable name Injector.
Lists all the current injector components available on the user's panel
