General Description
Controller CANNY 7 can be used as a master node in a single-wire data network Dallas® 1-Wire®, while it has the ability to only send requests for data from slave devices.
Any of CANNY 7 input-output channels can be used to connect the controller to 1-Wire bus. At the same time, that channel must be externally pulled-up to 5V with resistor 3-7k Ohm. Consistently reassigning driver channels, it's possible to arrange up to 11 independent connections 1-Wire. Wherein device addressing and device handling by address is not available, therefore, in 1-Wire mode it is possible to connect only one SLAVE node at a time to controllers' channel.
Driver Dallas 1-Wire in its operation uses controller channels' resources, but has a higher priority than discrete input-output driver.Thus, upon activation Dallas 1-Wire driver, for channels involved in to its operation, change values in associated registers of discrete input-output driver will be ignored.
The slave must have a permanent, rather than parasitic power.
Dallas 1-Wire® driver
Below is a description of the Dallas 1-Wire® driver registers.
Dallas 1-Wire® driver configuration registers.
To activate Dallas 1-Wire® driver, you need to select the controller channel number connected to Dallas 1-Wire® bus, in the appropriate driver register.
| Note:
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At any given time, the driver can work with only one of the connected Dallas 1-Wire® bus, when it is allowed to dynamically switch between buses in the implementation of the functional diagram.
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Sent requests management to get information from the slaves and control receiving of their responses (sensors poll) is performed by appropriate registers of 1-Wire driver.
| Note:
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To avoid data loss, when working with several Dallas buses, perform switching between them only after receiving responses from the slaves requested by the controller and processing or saving the data.
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Example of channel #5 configured to work with a temperature sensor DS18X20.
Dallas 1-Wire® Setup Registers.
| Address
|
Expected values
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| Dallas 1-Wire® Mode Setup register
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| 1...65535
|
=
|
driver activation and setting the device type (defined by a special constant of the constants directory);
|
| 0
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=
|
disconnect the channel from 1-Wire driver, return channel control to IO channels driver and allow status changing from the functional diagram.
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|
| Dallas 1-Wire® IO Channel Select Register
|
| 0...10
|
=
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set the channel number used by the controller to work with Dallas 1-Wire® bus .
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Channel configuration to operate in this mode is set by the following named constants:
| Parameter
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List of expected values
|
| Dallas 1-Wire® device type
|
DS18X20 temperature sensor, CP-Z reader in the DS1990A emulation mode, DS1990A reader
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Dallas 1-Wire® Request Registers.
With the help of Dallas 1-Wire® driver request registers , the user can specify the address of respondent slave node and send a request for data transfer.
| Address
|
Expected values
|
| Dallas 1-Wire® Request To Send Register
|
| 1
|
=
|
send a request for data to the slave;
|
| 0
|
=
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do not send a request for data to the slave.
|
|
| Dallas 1-Wire® Requested Device ID RAW Data Register SN0:FC
|
| 0...65535
|
=
|
register value: the lower part represent a device family identifier (FC), the upper part contains the first byte of the unique device address (SN0).
|
|
| Dallas 1-Wire® Requested Device ID RAW Data Register SN2:SN1
|
| 0...65535
|
=
|
register value: the lower part contains the 2nd byte of the unique device address (SN1), the upper part contains the 3rd byte of the unique device address (SN2).
|
|
| Dallas 1-Wire® Requested Device ID RAW Data Register SN4:SN3
|
| 0...65535
|
=
|
register value: the lower part contains the 4th byte of the unique device address (SN3), the upper part contains the 5th byte of the unique device address (SN4).
|
|
| Dallas 1-Wire® Requested Device ID RAW Data Register CRC:SN5
|
| 0...65535
|
=
|
register value: the lower part contains the 6th byte of the unique device address (SN5), the upper part contains ROM-code addressee checksum (CRC).
|
|
| Note:
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The setup registers of Dallas 1-Wire® 64-bit transmission destination ROM-code is only used to select a device on the Dallas 1-Wire® bus by its unique number (ROM-code), in case of multiple devices connected to the same bus. During operation with a single device on the bus, when its ROM- code unknown, set "0" value into all registers of Dallas transmission destination ROM-code.
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Dallas 1-Wire® Receive Registers .
During its operation, upon reception of responses from the slave devices to the controller data requests, according to Dallas 1-Wire® driver configuration, stored in its corresponding receiving registers.
General receive registers.
| Address
|
Return values
|
| Dallas 1-Wire® Data Set Ready Register
|
| 1
|
=
|
successfully received data from the slave node and it is available in Dallas 1-Wire® driver read registers;
|
| 0
|
=
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there is no actual data in the driver receive buffer.
|
|
iButton® DS1990A Receive Mode Registers.
| Address
|
Return values
|
| Dallas 1-Wire® Received Raw Data Register D0:FC
|
| 0...65535
|
=
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register value: lower part contains family key identifier (FC), higher part contains the first byte of unique key address (SN0).
|
|
| Dallas 1-Wire® Received Raw Data Register D2:D1
|
| 0...65535
|
=
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register value: lower part contains the second byte of unique key address (SN1), higher part contains the third byte of unique key address (SN2).
|
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| Dallas 1-Wire® Received Raw Data Register D4:D3
|
| 0...65535
|
=
|
register value: lower part contains the forth byte of unique key address (SN3), higher part contains the fifth byte of unique key address (SN4).
|
|
| Dallas 1-Wire® Received Raw Data Register CRC:D5
|
| 0...65535
|
=
|
register value: lower part contains the sixth byte of unique key address (SN5), higher part contains key checksum ROM-code (CRC).
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|
DS18X20 Receive Mode Registers.
| Адрес
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Returning values
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| DS18X20 Received Temperature Data Register: Integer Part
|
| 0...125
|
=
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modulo of integer part of temperature value measured by the sensor.
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| DS18X20 Received Temperature Data Register: Fractional Part ( x 0.0001)
|
| 0...9999
|
=
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modulo of decimal part of temperature value measured by the sensor.
|
|
| DS18X20 Received Temperature Data Register: Sign (0 = above zero; 1 = below zero)
|
| 0
|
=
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the temperature measured by the sensor is above zero;
|
| 1
|
=
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the temperature measured by the sensor is below zero.
|
|
| Note:
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When receiving in DS18X20 mode, temperature sensor duty cycle, those send requests via Dallas transmission start register, should not be less than 750ms.
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Example of a functional diagram working with DS18X20 temperature sensor.
temperature sensor poll, connected to the channel #5, carried out 1 time per second. When receiving data from DS18X20, in Dallas 1-Wire® Data Set Ready Register appears value "1" and data from the temperature reading registers, with help of D flip-flops, is stored in respective named networks for further processing.
See also
CANNY 7
CANNY 7, I²C Driver
