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:
|
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.
|
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:
|
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.
|
Example of channel #5 configuration to use with a temperature sensor DS18X20.
Dallas 1-Wire® Setup Registers.
| Address
|
Expected values
|
| Dallas 1-Wire® configuration register
|
| 1...65535
|
=
|
driver activation and setting the device type (defined by a special constant of the constants directory);
|
| 0
|
=
|
disconnect the channel from 1-Wire driver, return channel control to IO channels driver and allow status changing from the functional diagram.
|
|
| Dallas 1-Wire® IO Channel Select register
|
| 0...10
|
=
|
set the channel number used by the controller to work with Dallas 1-Wire® bus .
|
|
The channel configuration for operation in this mode is set by the following named constants:
| Parameter
|
List of expected values
|
| Dallas 1-Wire® device type
|
DS18X20 temperature sensor, CP-Z reader in the DS1990A emulation mode, DS1990A reader
|
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
|
Expected values
|
| Dallas start transmission register
|
| 1
|
=
|
send a request for data to the slave;
|
| 0
|
=
|
do not send a request for data to the slave.
|
|
| The setup registers of Dallas 64-bit transmission destination ROM-code 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).
|
|
| The setup registers of Dallas 64-bit transmission destination ROM-code 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).
|
|
| The setup registers of Dallas 64-bit transmission destination ROM-code 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).
|
|
| The setup registers of Dallas 64-bit transmission destination ROM-code 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:
|
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.
|
Dallas 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
|
Return values
|
| Register the presence of the received data Dallas
|
| 1
|
=
|
successfully received data from the slave node and it is available in Dallas driver read registers;
|
| 0
|
=
|
there is no actual data in the driver receive buffer.
|
|
Reception in CZP / DS1990A mode.
| Address
|
Return values
|
| Регистр чтения 64-битного ROM-кода устройства Dallas SN0:FC
|
| 0...65535
|
=
|
значение регистра: младшая часть содержит идентификатор семейства ключа (FC), старшая часть содержит первый байт уникального адреса ключа (SN0).
|
|
| Регистр чтения 64-битного ROM-кода устройства Dallas SN2:SN1
|
| 0...65535
|
=
|
значение регистра: младшая часть содержит второй байт уникального адреса ключа (SN1), старшая часть содержит третий байт уникального адреса ключа (SN2).
|
|
| Регистр чтения 64-битного ROM-кода устройства Dallas SN4:SN3
|
| 0...65535
|
=
|
значение регистра: младшая часть содержит четвертый байт уникального адреса ключа (SN3), старшая часть содержит пятый байт уникального адреса ключа (SN4).
|
|
| Регистр чтения 64-битного ROM-кода устройства Dallas CRC:SN5
|
| 0...65535
|
=
|
значение регистра: младшая часть содержит шестой байт уникального адреса ключа (SN5), старшая часть содержит контрольную сумму ROM-кода ключа (CRC).
|
|
Прием в режиме DS18X20.
| Адрес
|
Возвращаемые значения
|
| Регистр чтения показаний температуры: целые градусы Цельсия
|
| 0...125
|
=
|
модуль целой части значения измеренной датчиком температуры.
|
|
| Регистр чтения показаний температуры: десятитысячные доли градуса Цельсия
|
| 0...9999
|
=
|
модуль десятичной части значения измеренной датчиком температуры.
|
|
| Регистр чтения показаний температуры: sign (0 = above zero; 1 = below zero)
|
| 0
|
=
|
the temperature measured by the sensor is above zero;
|
| 1
|
=
|
the temperature measured by the sensor is below zero.
|
|
| Note:
|
When receiving in DS18X20 mode, temperature sensor duty cycle, those send requests via Dallas transmission start register, should not be less than 750ms.
|
Example of a functional diagram to work with temperature sensor DS18X20.
temperature sensor poll, connected to the channel #5, carried out 1 time per second. 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
