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Difference between revisions of "CANNY 7, Dallas 1-Wire Driver"
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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. | 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. | ||
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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. | 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. | ||
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| + | Sensor connection circuit. | ||
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| + | [[File:6_12_2_3.png|800px|center]] | ||
== See also == | == See also == | ||
Latest revision as of 13:15, 5 February 2018
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 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. |
Example of channel #5 configured to work with a temperature sensor DS18X20.
Dallas 1-Wire® Setup Registers.
| Address | Expected values | ||||||
|---|---|---|---|---|---|---|---|
| Dallas 1-Wire® Mode Setup register |
| ||||||
| Dallas 1-Wire® IO Channel Select Register |
|
Channel configuration to operate 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 |
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 |
| ||||||
| Dallas 1-Wire® Requested Device ID RAW Data Register SN0:FC |
| ||||||
| Dallas 1-Wire® Requested Device ID RAW Data Register SN2:SN1 |
| ||||||
| Dallas 1-Wire® Requested Device ID RAW Data Register SN4:SN3 |
| ||||||
| Dallas 1-Wire® Requested Device ID RAW Data Register CRC:SN5 |
|
| Note: | 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. |
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 |
|
iButton® DS1990A Receive Mode Registers.
| Address | Return values | |||
|---|---|---|---|---|
| Dallas 1-Wire® Received Raw Data Register D0:FC |
| |||
| Dallas 1-Wire® Received Raw Data Register D2:D1 |
| |||
| Dallas 1-Wire® Received Raw Data Register D4:D3 |
| |||
| Dallas 1-Wire® Received Raw Data Register CRC:D5 |
|
DS18X20 Receive Mode Registers.
| Address | Returning values | ||||||
|---|---|---|---|---|---|---|---|
| DS18X20 Received Temperature Data Register: Integer Part |
| ||||||
| DS18X20 Received Temperature Data Register: Fractional Part ( x 0.0001) |
| ||||||
| DS18X20 Received Temperature Data Register: Sign (0 = above zero; 1 = 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 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.
Sensor connection circuit.
