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.
Registers 1-Wire driver
Below is a description of the 1-Wire driver operation control registers.
Registers 1-Wire driver configuration.
To activate the 1-Wire driver, need to select the controller channel number connected to 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 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 losing data 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 configuration to use with a temperature sensor DS18X20.
1-Wire driver configuration registers.
Адрес
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Expected values
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Dallas configuration register
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1...65535
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=
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driver activation and setting the device type (defined by a special constant of the constants directory);
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0
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=
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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 channel number register
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0...10
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=
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set the channel number used by the controller to work with 1-Wire bus .
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The channel configuration for operation in this mode is set by the following named constants:
Parameter
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List of expected values
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1-Wire device type
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DS18X20 temperature sensor, CP-Z reader in the DS1990A emulation mode, DS1990A reader
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1-Wire transmit registers.
With the help of 1-Wire driver transmission registers , the user can specify the address of the respondent slave node and send a request for data transfer.
Address
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Expected values
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Dallas start transmission register
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1
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=
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send a request for data to the slave;
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0
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=
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do not send a request for data to the slave.
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The setup registers of Dallas 64-bit transmission destination ROM-code SN0:FC
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0...65535
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=
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register value: the lower part represent a device family identifier (FC), the upper part contains the first byte of the unique device address (SN0).
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The setup registers of Dallas 64-bit transmission destination ROM-code SN2:SN1
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0...65535
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=
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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).
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The setup registers of Dallas 64-bit transmission destination ROM-code SN4:SN3
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0...65535
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=
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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).
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The setup registers of Dallas 64-bit transmission destination ROM-code CRC:SN5
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0...65535
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=
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register value: the lower part contains the 6th byte of the unique device address (SN5), the upper part contains ROM-code addressee checksum (CRC).
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Note:
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The setup registers of Dallas 64-bit transmission destination ROM-code is only used to select a device on the 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 it ROM- code unknown, set "0" value into all registers of Dallas transmission destination ROM-code.
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1-Wire driver receive registers .
In operation, upon receiption of responses from the slave devices to the controller requests, data, according to the 1-Wire driver configuration, stored in its corresponding receiving registers.
General reception registers.
Address
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Return values
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Register the presence of the received data Dallas
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1
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=
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successfully received data from the slave node and it is available in Dallas driver read registers;
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0
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=
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there is no actual data in the driver receive buffer.
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Reception in CZP / DS1990A mode.
Address
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Return values
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Регистр чтения 64-битного ROM-кода устройства Dallas SN0:FC
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0...65535
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=
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значение регистра: младшая часть содержит идентификатор семейства ключа (FC), старшая часть содержит первый байт уникального адреса ключа (SN0).
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Регистр чтения 64-битного ROM-кода устройства Dallas SN2:SN1
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0...65535
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=
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значение регистра: младшая часть содержит второй байт уникального адреса ключа (SN1), старшая часть содержит третий байт уникального адреса ключа (SN2).
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Регистр чтения 64-битного ROM-кода устройства Dallas SN4:SN3
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0...65535
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=
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значение регистра: младшая часть содержит четвертый байт уникального адреса ключа (SN3), старшая часть содержит пятый байт уникального адреса ключа (SN4).
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Регистр чтения 64-битного ROM-кода устройства Dallas CRC:SN5
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0...65535
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=
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значение регистра: младшая часть содержит шестой байт уникального адреса ключа (SN5), старшая часть содержит контрольную сумму ROM-кода ключа (CRC).
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Прием в режиме DS18X20.
Адрес
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Возвращаемые значения
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Регистр чтения показаний температуры: целые градусы Цельсия
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0...125
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=
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модуль целой части значения измеренной датчиком температуры.
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Регистр чтения показаний температуры: десятитысячные доли градуса Цельсия
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0...9999
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=
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модуль десятичной части значения измеренной датчиком температуры.
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Регистр чтения показаний температуры: знак (0 = выше нуля; 1 = ниже нуля)
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0
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=
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измеренная датчиком температура не ниже нуля;
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1
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=
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измеренная датчиком температура ниже нуля.
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Примечание:
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При приеме в режиме DS18X20 период опроса датчика температуры, т. е. отправки ему запросов с помощью регистра начала передачи Dallas, должен быть не менее 750мс.
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Пример функциональной диаграммы работы с термодатчиком DS18X20.
Опрос термодатчика, подключенного к каналу №5 контроллера, осуществляется 1 раз в секунду. При получении данных от DS18X20, в регистре наличия принятых данных драйвера Dallas появляется значение «1» и данные из регистров чтения показаний температуры, с помощью D-триггеров, сохраняются в соответствующие именованные сети для дальнейшей обработки.
See also
CANNY 7
CANNY 7, I²C Driver